The truth about Coolants

robertobaggio20 · Mar 3, 2011

A set of coolant posts showed up recently with the usual questions about it. I have spent much time looking into this topic and would like to share what i've gleaned from the web, from others here on the fest, and from my own trials with my ride. I believe i understand this topic in its near entirety. What i have discovered will prove controversial for some.

Before that, let me state the baseline for clarity. Coolant chemicals were created to both lower the melting point and raise the boiling point of water. This helps coolant stay liquid in the winter and handle the normal operating temperatures of your engine without boiling over. (A pressurised cooling system also helps to raise the coolant's boiling point, for the same reason).

So now, onto the facts :

1. All coolants are compatible with each other. They can be mixed with each other with no problems.

2. Coolants have different colours due to different colouring DYES added to the coolant, not different active chemicals.

3. All coolants use ethyl glycol as their base chemical. The more of this chemical you have in your system, the lower your melting point and higher the boiling point of the water-coolant mix.

4. 100% ethyl glycol is not required - too expensive, and is a case of over-engineering for the car's heating systems as the car is designed to run at around 100 degrees celsius or around there.

5. Manufacturers add various coloured and aromatic dyes to their coolant to accomplish three objectives :

a. Brand identity for marketing purposes. This can be used to more easily convince people that "my coolant is better than his coolant" etc.

b. Visibility. Ethyl glycol is colourless. Adding colour enables you to see the coolant more easily through the expansion tank, and spot any leaks in your cooling system that much more easily as compared to a colourless leak. People are also less likely to mistake it for water and drink it as well.

c. The ability to smell the coolant. Ethyl glycol is odourless. Aromatic chemicals are added to enable you to smell the coolant. The main reason they do this is so that any coolant leaks in the engine bay will cause the strong coolant smell to immediately invade your cabin (air reaching the cabin does get sucked from your engine bay before going through your microfilter)...and the driver is instantly alerted to a possible problem before the leak gets so bad that the engine begins to overheat.

[ This simple fact helped me arrest two situations recently which involved ruptured coolant hoses. I have become a firm believer ever since. ]

6. Manufacturers also add anti-electrolytes to their coolant. This will suppress rust formation. They are also known as rust or corrosion inhibitors. I'm not exactly sure which are the specific chemicals involved but they are definitely NOT rocket science either so all the manufacturers use essentially the same chemicals.

7. Newer engines use an all-aluminium alloy cylinder head and block. This stuff does not rust at all. I was told that it has other problems, so the corrosion inhibitors in regular coolant does help too, but I can't confirm this. Stopped my research - pointless as my car has an iron block.

8. There's a company called Evans that sells a zero pressure cooling fluid called NPG+ (this is a brand name). Its basically 100% propanol which (if i'm not wrong) is an isomer of ethyl glycol, and is thus non-aqueous i.e. does not involve any water. This stuff is expensive and after consultation with bentley's ghost, i decided that it was not worth the continuous investments involved compared to other things like high-flow water pumps, low temp thermostats, silicone or steel lined coolant hoses, new expansion tank seals, new coolant piping etc. There's no harm in using it at all, many have done so with great results, but I'm not totally convinced that the claimed benefits of eliminating in-situ micro vaporisation in the cylinder head is really significant. Plus, cheap coolant is well cheap, and enables you to affordably flush your engine twice a year, which is something that i find really fun to do for some inexplicable reason.

9. There are mechanics out there who have gone on record to say that only BMW coolant is safe for our cars. Of course, if you're a mechanic, and you're going on public record, and you're making a statement that covers the whole world, and perhaps if you wish to be nice to your sponsors, you're not likely to make any statements which involve ANY risk whatsoever, will you? And you can't be taking any risk when you say that bmw coolant is best for bmw, toyota antifreeze is best for toyota, etc etc. Even if anything goes wrong, the billion-dollar manufacturers will race in to back you up. Plus most mechanics are not educated or do not have a scientific bent in their approach to things, so they rarely take risks about chemicals and the physics of the engine etc.

10. The auto industry, and basically, capitalist industry itself consistently twisting the truth, misleading and not-infrequently lying to the public in order to fortify their own profits, is nothing new is it? Can you blame them when there are legions of hypnotised gullible people around? So caveat emptor, wide reading and good relationships with like-minded enthusiasts helps to educate one against nonsense, which will ultimately have a direct and measurably beneficial effect on one's bank account and peace of mind. If you don't take that approach, not only will you be a victim of the loads of bull**** out there, you'll become its perpetrator as well when you spread your misinformation to others.

11. My advice to you? Chuck the bmw coolant immediately. Add 2 cans of concentrated cheap luminescent yellow/green coloured strongly sweet smelling coolant into your radiator, and keep one can in your trunk at all times. Please see the following picture for a sample, in fact please see three pictures, of the coolant I use, that's made in San Diego :

If possible, get a refund or an exchange for your spare bottles of bmw coolant. It costs nearly 4 times more, is not as bright as the cheap stuff, and does not have a strong smell at all. You need these two elements for reasons mentioned above. There are no particularly brilliant proprietary corrosion inhibitors in bmw's coolant worth paying a premium for as well.

Its your money and your car. If you want to take the risk of using a very mildly aromatic coolant like what bmw uses, that's up to you. Yes, you read right, to me, using bmw coolant is RISKY when compared to cheaper, strong smelling stuff particularly when it comes to older cars, engines, hoses, radiators, etc. Of course, paying more for coolant does ultimately help to stimulate the economy, create more jobs and end world hunger and enable each child to get 1 free pass to Disneyland every year, so I suppose it is worth doing. lol

Everything I've written above can be verified after reading sufficient articles on the net. So please, do take my advice, I am using it !

Monsignor · Mar 3, 2011

Roberto, would you mind writing a detailed write-up on the coolant flush. Sort of like a hot-to? DIY? i want to make sure i do it to perfectly to the strict Roberto standards...:thumbup:

robertobaggio20 · Mar 3, 2011

Coolant Flush

Hi Padre,

How could I refuse you sir?

Ok before I continue, some overarching statements of fact to set the stage.

A. It is not possible to flush your coolant properly due to the thermostat. I'll explain further later.

B. Most anti rust coolant flushes are just coolants themselves and do not contain any active anti-scaling compounds within them. Do not ever waste money on these products. Resist the temptation to do so - its strong i know ! You're not doing anything helpful for your car with these products.

C. It is only possible to remove all the rust in your engine when you do an overhaul and use a specially constructed tool (Rick? still waiting on you here dude) to gently scrape the coolant passages in the block and the head.

D. Cummins, the well known engineering company, actually sells an anti-rust solution that is supposed to lift off rust. I'm going to try that sometime in the next few months.

E. I spotted an ad for a small american company that claims to have created an rust removing solution for radiators. Have lost that link (damn stupid of me) and have not tried it yet.

F. There is no need to use distilled water in your radiator. Coolant has more than sufficient anti-electrolytes to overwhelm the peanuts ions found in tap water.

G. Have taken the pedal off the metal for this issue because i've come to accept that there will always be a little rust in the system, and that this little rust will not impede anything up in the block, cylinder head, water pump, hoses, coolant temp sensors and radiator. The car was designed with this in mind. All you need to do is, following a thorough 3-cycle flush of your radiator, flush your radiator at least once every year. Don't wait for 2 years - its so easy to do this and its kinda fun, and while its going on in the background you can do many other things to your car simultaneously. All of this will only make sense to enthusiasts and diy-types.

Right - so how do you flush your engine thoroughly? ( Until internalised, please print the following and keep it with you at the car while carrying this out, to ensure you do not forget any steps.)

Part 1/3

1. Remove radiator cap and bleed screw. Do this very carefully if the engine is hot. If it is hot, make sure you're wearing gloves and take care not to get your arms burnt as you do things.
2. Remove top radiator hose at the radiator connection - left side of the engine near the top. You can leave the engine connection as it is. Move the disconnected section down below or away from the rad neck as best as you can without damaging the hose.
3. Unscrew radiator drain plug - somewhere under the air box - you'll likely need to remove the air box to gain access so this is best done when you're also cleaning/changing the air filter.
4. Unscrew and disconnect the lower radiator hose at the radiator connection - Right side of the engine near the bottom. You can leave the engine connection untouched. Move the disconnected section down below or away from the rad neck as best as you can without damaging the hose.

( The above takes around 5 minutes or less to do )

5. Pull a long water hose and stick it into the expansion tank.
6. Start the water running - medium to high flow. Let the water flow out everywhere for 5 minutes.
7. Remove the hose from the expansion tank and stick it into the upper radiator hose's radiator neck. (Just discovered the brilliance of this like 3 weeks back).
8. Turn on the water to medium or high flow. Let it run for five minutes.
9. Remove the hose. Aim it at the bleed screw's hole at the top of the radiator.
10. Turn on the water for 2 minutes.
11. Stop the water. Let all the water drain out from the system.
12. Reconnect the upper and lower radiator hoses and tighten the radiator drain plug - do this slowly but properly, don't use too much force as the connection that is not made of strong plastic.

( This process will take around 15 minutes. )

13. Leaving the bleed screw and rad cap off, fill up the system with water and some $3 coolant. Alot of water will be needed, fill up to the top of the expansion tank, wait for the water levels to go down, and fill it up again to the top.
14. Start the engine and bleed the radiator as best as you can.
15. Let the engine run for 5-10 minutes (do something else in the background such as fixing the air box back) then bleed the radiator again.
16. Reinstall the bleed screw, fill up water to the top of the expansion tank, reinstall the rad cap, and then shut down the engine or drive off somewhere else if you wish. There is no need to bleed the radiator any further (m50 engines).

This part will take anywhere from 10-20 minutes.

You are done with part 1/3. Total time - 30-45 minutes. Take more time than less if you're doing this for the very first time. Subsequent flushes (parts 2/3 and 3/3) can be faster....up to as short as 20 minutes, but no shorter please.

Part 2/3 : Repeat the exact same process within 7-14 days, ensuring that the car has been constantly used in that interval. Ensure that some highway driving is involved along the way - the more, the merrier. Don't execute step this earlier than 7 days.

Part 3/3 : Repeat the exact same process within 7-14 days of doing Part 2/3, ensuring the car has been constantly driven in that interval. Ensure that some highway driving is involved along the way - the more the merrier. Don't execute this step earlier than 7 days. Add TWO cans of $3 coolant concentrate this time. Always use 2 cans on the last flushing cycle.

Thereafter, do one flush no later than once every 12 months. For efficiency, its best to coincide this together with other regular servicing, such as air and fuel filter refreshment, waxing, etc. Doing more than one cycle at this stage doesn't really help - only do more if you notice excessive amounts of rust in the coolant being drained out.

For more than 1 year, i was flushing my engine in a different way. I would disconnect the top rad hose, the rad cap and the bleed screw but not the bottom rad hose and would not unscrew the drain plug. I would stick a garden hose into my expansion tank, turn it on to full blast, and run my engine at idle. I'd let it go like this for 30 minutes, then reconnect the hose back, add $3 coolant, bleed the radiator, then finish up.

I later realised that i was wasting my time and lots of water. When cold water circulates through the system, the thermostat closes nearly shut (it is never fully shut). This prevents much coolant from leaving the engine block and coming out to the radiator loop, and falling out through the open top radiator hose.

Rust is predominantly found in the engine, and not anywhere else. That's the target. And, unless you're using a hose that channels nearly boiling water, it will not be possible to get everything out via diy flush.

The only way rust leaves the block is when the coolant stuck in the block circulates out. And this happens only when the thermostat is fully open, which happens only when the engine is fire- breathing hot, which occurs during highway driving typically. You can leave your engine to idle for 2 hours, it won't reach this point, so don't bother. That's why you need to drive between flushes, and that's also why you need to unscrew the drain plug and feed the hose into the top rad neck...these two steps will ensure that the RADIATOR'S loop becomes totally cleaned of rust, which is really all that can be done realistically, and as you do this over and over again, more and more rust from the engine circulates out to the radiator where it can be drained.

I am not sure, but i've been told that the engine block has a coolant drain plug. This is supposedly accessible when the car is jacked up. I need to check this out. It would be the best way to clean out the block. But its hard to do and not necessary as there'll always be rust in the system - its ok.

ricks5series · Mar 3, 2011

Roberto,
Your constant search to remedy situations for our E34's are amazing and I'm sure many including myself appreciate the time you take to do these write ups.

That being said, allow me if you will, to suggest a method I've been using on my corvette.

This will address flushing the entire system, engine included, while the engine idles up to normal operating temperature thus allowing the thermostat to open.

In the photo "Y connection" I use a standard Y connection for a washing machine which you'll find at any hardware store, Lowes, HomeDpot, ACE, etc.

I've connected this "Y" hose to two separate washing machine hoses, attaching the fitted ends to the "Y" and cutting the ends off the other side. I replaced the cut side with brass fittings which fit the threaded drain holes from each side of the V8 engine. In the case of our M50, there "is" a drain plug underneath the exhaust manifold towards the read of the block.

I'm showing you the pictures of my set up for the Corvette to give you a visual but a "Y" connection is not needed for our application.
All you who have to do is purchase one washing machine hose, one side fits into a garden hose while the other side is cut and replace with the thread fitting into the M50's engine drain plug.

(Car will need to be jacked up on stands) Make sure the car is secure. As a safety precaution, even when the car is on jack stands, I "always" leave the hydraulic jack pumped as well. Do not ever solely rely on just a hydraulic jack!

Take your home made hose connection and screw the brass fitting into the engine block and the other end into the garden hose. You can either run it off your home water supply or connect it to your water heater (if it's accessible) in order to run heated water. I use the water heater method.

Before I begin, I remove the radiator cap and stick one of those Prestone plastic fittings which direct extracted water away from the engine. In this case you will need to duct tape it into place due to the smaller diameter and will work because the pressure is low. Also, turn your heater setting to full hot. You want this part of the system to be flushed out as well.

I then start the engine and monitor the temp gauge while it is idling. When the temp gauge reaches 1/4 I slowly turn the water on and go back and monitor the temperature gauge. This is important because you want to make sure the engine doesn't exceed normal operating temperature.

So now the car is running, thermostat is open and you just keep watching the expelled water come out of the radiator until it's clear. This process addresses the entire cooling system.

In the photo with the engine, note the drain plug is just below cylinder # 4.

Now, I have not set this up on the M50. From my observation while removing the exhaust manifold, I recall limited space between the block and the manifold which might make it difficult to connect the hose. I may be wrong but I'm going to look into it a bit closer. If so, I may have a solution. I could replace the plug with a right angle brass fitting pointing downward and then cap the other end with a plug.

There you have it.

robertobaggio20 · Mar 3, 2011

ricks5series said:
Now, I have not set this up on the M50. From my observation while removing the exhaust manifold, I recall limited space between the block and the manifold which might make it difficult to connect the hose. I may be wrong but I'm going to look into it a bit closer. If so, I may have a solution. I could replace the plug with a right angle brass fitting pointing downward and then cap the other end with a plug.

There you have it.

Is it possible to create a right angle brass fitting fixed into the drain plug, facing UP, in such a way that it is accessible from the passenger's side of the engine bay ? Please think about it....it doesn't matter as much if it looks odd.

rdorman · Mar 3, 2011

There where so many errors I just stopped reading.....

robertobaggio20 · Mar 3, 2011

....and why not start posting, to correct those errors?

We could all benefit by your knowledge.

Rick, thank you for your suggestion, but draining the block does not seem to be feasible if i'm diying without any jacks. Are you suggesting that we fit a custom fitting into the block's coolant drain plug (thank you for confirming that it exists) and fixing it in such a way that it is accessible whenever we want to flush the engine?

To flush the engine after the new fitting is installed, will the car have to be jacked up? If it would, then i must respectfully suggest that most of us would neither possess nor acquire the resources to accomplish this, and so this method would not be workable over the long term. If its a one-time fitting when the car is winched up, and thereafter, accessible without the car needing to be jacked, well that would be thinkable.

Please clarify sir if time permits thanks.

rgds,
Roberto

ricks5series · Mar 4, 2011

Roberto,
This is simply to give you a general idea of what I am talking about. This is only a sample and is not the actually fitting I will use. I couldn't find any metric angle fitting with a female thread on the other end, perhaps I'll have more luck tomorrow.

In any case, I'm looking for a angle fitting with a male thread (14mm, 1.5 pitch) which will screw into the block and a a female 14mm, 1.5 on the other end so that I can connect a 5" pipe pointing down. The pipe will obviously be threaded at the end so I can connect the custom hose to it, then cap it when I'm done flushing the system.

robertobaggio20 · Mar 6, 2011

This initial post by Dna_Diesel and its reply has been relocated to this thread from this one http://www.bimmerfest.com/forums/showthread.php?p=5895961#post5895961

DnA Diesel said:
A reduced-silicate, nitrite-free, phosphate-free formulation, mixed with de-ionized/de-mineralized water is the best for your M60B40-powered E34, no matter what colour or scent has been added to the coolant. This article from Machinery Lubrication is one of the best, neutral pieces I've seen. BMW coolant (G-48, blue) minimizes the deposition of unwanted non-metallic precipitates on the metal of the internal passages of the engine which reduce heat transfer and can impede coolant flow. Note that some silicates are required to minimize corrosive/electrolytic effects on the Nikisil and Alusil alloys (note the "sil" in their names). Some say that Zerex G-05 (yellow), a low-silicate, phosphate-free coolant, can be used in lieu of OEM G-48, however, you should note that G-05 formulations, while hybrid organic acid in nature like G48, still contains SOME nitrites, and is thus NOT APPROVED by BMW as a replacement for G-48 coolant. BASF is the OEM manufacturer of G-48 coolant for BMW. See BASF/Glysantin fact sheet here for applications and their list here for OEM approval specifications.

In a nutshell, whatever coolant you use, it should:

- contain moderate amounts of silicates (reduced corrosion of Nikisil/Alusil alloyed engine blocks)
- be phosphate-free (minimizes precipitation of calcium or magnesium phosphates)
- be nitrite-free (minimizes nitric-acid formation and corrosion) <- NITRITES are BAD

...and mix it with pure, de-ionized/de-mineralized water.

It goes without saying that a regular visual inspections of your entire cooling system, even inside of your No. I and No. II inspection periods, should be the rule, rather than relying on smells or leaks to tell you when something is wrong.

I've fed my 95 540i/6 G-48 for a decade and only had one well-known problem with a composite plastic fitting at the auxiliary pump/heater-valve assembly, but that was due to age of the plastic in conjunction with a poor part design (M60-powered E34 owners, look at this assembly carefully...if it hasn't broken on you yet, it's just around the corner.)

Regards
D

Hi D,

Thank you for those good articles. Have saved them in my archives for posterity. I have some questions that I hope you can help me with.

1. Would you say that most off the shelf coolants now are the ELC type with carboxylates inside? It has been more than 10 years since these were invented and should have hit the general market

2. Would you say that most OEM coolants are the ELC type with carboxylates inside?

3. If a coolant is made with carboxylates, would the manufacturer recommend that you renew it once every 2 years?

4. Is it fair to say that any off the shelf coolant that you find today that is marked "radiator safe" is also safe for modern cars which are made of full aluminium-alloy blocks and heads? I.e. would any coolant you find these days be absent nitrates and phosphates ? I understand that it may or may not contain carboxylates either as a pure carboxylate concoction or a hybrid mixture with silicates.

5. Say i purchase some pH paper strips. I test them with some of my coolant fluid. The pH is at 7.0 or higher. Would you safely say then that this coolant is still good for continued use? If so, it might be a good idea to pick up some pH paper as its so cheap. Would retail pH paper be sufficiently accurate for our purposes here?

6. Does it really matter that you use distilled water in your cooling system? Normal treated tap water that's safe for drinking and which comes from a public utility channel has trace levels of minerals etc which are comprehensively and instantly overwhelmed by coolant concentrate. Distilled water is cheap, but well if it doesn't make any significant difference, does it make sense to go to that extra trouble ? I'm looking at this in practical terms which do not just involve topping off coolant or changing it once every 2 years, but also where annual coolant system flushes are carried out (and this is done most usually and most easily with a running garden hose connected to a public water supply).

And I'd like to clarify that using smells and bright colours is an effective secondary warning system against sudden leaks and burst hoses. It is not and will never be a substitute for regular visual inspections of all hoses and coolant system fittings etc to ensure that everything's ok. Inspection happens automatically and unconsciously when people regularly maintain their vehicles and when people have pride in their engines, which causes them to constantly pop the bonnet and just look at everything for no good reason - i'm sure we are all guilty of this.

Having said that, unless you're going to change every single coolant hose in your car and reinforce the hose joints with steel braided tape/hose thread, you're running an unnecessary risk by avoiding bright sweet smelling coolant. We are dealing with very old cars and in the interests of keeping maintenance costs manageble and yet be responsive to freak problems, i'd still use this coolant for secondary protection. It has literally saved my engine at least twice in the past few months.

DnA Diesel · Mar 6, 2011

Roberto, my engineering expertise is in another domain (aerospace/mechanical and electrical), however, the fundamentals of understanding the linkage between how folks designed systems (engines/cooling systems in this case) and the ongoing in-service support of the systems is important. Equally important is the appreciation of appropriate preventive maintenance, scheduled to address reduced protective levels inside of the time cycle that damage to the system to be done.

From my research (a lot of tech studies in the discipline and familiarizing myself with ASTM test methods) I found that BMW had specified G-48 coolant for the three reasons noted earlier in the thread: 1) moderate silicate content to minimize electrolytic corrosion of the high-silicon content alloy in the Nikisil and Alusil engine blocks through a deposition of a thin silicate layer on the metallic surfaces of the engine block (about 200-250ppm silicate is the norm) [note that silicates themselves do not chemically reduce electrolytic corrosion, only through a physical coolant-to-metal barrier], 2) phosphate-free to minimize the precipitation of calcium and magnesium phosphates resulting from high mineral content of mixing water, with an aim of minimizing the scaling within smaller coolant passages that would restrict coolant flow, and finally, and specific to BMW and SAAB (and VWAG until the late 2000s) nitrite-free - nitrites in solution are used to reduce cavitation of both water pumps and around wet-sleeve cylinder liners, primarily in heavy-duty diesel engines. BMW and SAAB engineers must have decided that their coolant circulation systems were designed appropriately enough that the benefit of nitrites in reducing cavitation were not worth the increase in corrosive effects that nitrites can and do have on other cooling system components.

To qualify the following, I don't know this stuff nearly as well as my Chem Eng buddies...that said, the term "carboxylates" is associated with both OAT (organic acid technology, use of boric acid is common) and HOAT (hybrid organic acid technology) formulations. Non-hybrid OATs (like Dex-Cool) rely primarily on the carboxylates to buffer the coolant. HOATs rely both on carboxylates to inhibit corrosion and buffer (stabilize pH levels) the coolant/water mix in addition, as well as an inorganic additive package to enhance the stability of the coolant over time. OATs (more so than HOATs) are designed to be used for longer service periods because their properties are generally not related to time, but rather inherent to the overall composition of the coolant itself for the most part, vice being a carrier for an additive package that is 'consumed' over time. The old inorganic additive technology (IAT - the green stuff) relied primarily to additives to the base ethylene-glycol base, and over time, these additives would become consumed, much like you see sacrificial zinc anodes attached to ships hulls to, through chemical reduction, reduce corrosion on the actual vessel and its components (propellers, fittings, rudder, etc...). Interestingly, some heavy-duty HOAT-type coolants, particularly in on/off-road heavy diesel service use "extender" packages to "boost" the inorganic additive packages, which are not normally available to the non-commercial public. These packages are usually added to the coolant systems of Class-8 highway trucks at around the 2-3 year point to extend the service life of the coolant to ~5-6 years (although more closely related to hours of engine operation, vice straight calendar time). Regarding composition of the coolant, if you see the word "amine(s)" in the product information, that means that there is a nitrogen portion to the carbonyl acid element (amine from ammonia, NH3), and this should be avoided, I would think, as the potential freeing of the nitrite element could act counter to the intent of BMW's specification to be nitrite-free.

Regarding your questions specifically, Roberto, I'd think that:

1, 2: Yes, most coolants (ELC or conventional) are now carboxylate-based,

3: I'd stick with the OEM's recommendations for changing fluid (many coolant manufacturers state that the fluid will retain properties longer, but to follow OEM drain periods)

4: "Radiator-safe" probably refers to low-nitrate (reduced corrosion) and low-phosphate (reduced sediment/precipitation) content. Silicates actually have a scouring effect, particularly at higher concentrations, so I don't think silicates are a major factor in "radiator-safe" claims.

5: Re: pH, I don't think that's a good indicator on its own. Look at a spec sheet for Zerex G-05...it has a 50/50-mixed nominal pH of 8.0 with an acceptable range of 7.5 to 11 (rather basic), but the pH in no way indicates the effectiveness of the other remaining additives or components. You could use it as an indicator that if the pH was BELOW the min (for G-05 7.5pH) that the coolant is no longer compliant with the manufacturer's product specifications and should be replaced.

6: If you know (by testing) that your household water is low in minerals, then you should be okay. Based on min chlorine content of 25ppm, you could use that as a guide (I'm assuming the calcium and magnesium in tap water should be in similar ranges ~25ppm.)

At the end of the day, the servicing that a car owner does on his or her vehicle is one of choice, and investment. If one chooses to put a particular coolant in their car, they should do so knowing what the long-term effect will be. Yes, there can be frustration where it seems the OEM-recommended solution is ridiculously expensive. That seems the case with BMW-approved G-48 coolant, but I think this is due to the relatively low volumes world-wide of manufactured G-48 compliant coolant. Only BMW and SAAB (to the best of my knowledge) mandate G-48 currently. Could you use G-05 (or other low-silicate, phosphate-free coolant)? Sure. Would the nitrites in the G-05 formulation lead to unintended corrosion, probably, but just how much, I'm not sure. Would the lack of any silicates, and higher nitrites and amines in a Dexcool form

This quote from Valvoline-Zerex (link) is a pretty good summation of how a car owner should select coolant to best care for their vehicle. It is interesting to note, that Zerex (which used to, but no longer manufactures G-48 coolant formulations) is careful to only "recommend" G-05 for BMW (and SAAB) products vice say that G-05 is "OEM-approved" (by BMW), as they know that BMW still does not approve of G-05 because of the formulation's high nitrite content. That said, G-05 is probably the best "if you can't find a G-48" coolant available.

Perhaps one of the most important aspects to look for when next shopping for antifreeze/coolant is approval from the maker of your car. Currently, there is no "one size fits all" solution that is approved for use in newer cars. And filling your cooling system with the wrong solution may result in serious adverse effects.

Products marked APPROVED have been subjected to years of field and lab testing by your car's manufacturer and are certain to provide the best performance and protection. Also, use of these products will ensure your car's warranty remains intact. The same cannot be said for using non-approved products, which may end up causing more problems than they solve. Some quality antifreeze/coolant producers even print the makes that have approved their products for use. This is always the best way to go.

As a car owner in today's fast-paced world, there are really only two key things to know when it comes to your car's antifreeze: Drain and replace it according to the manufacturer's recommendations (usually found in the owner's manual). And use an antifreeze/coolant that is approved by your manufacturer for use in your car. You-and your car-will be happier and more confident regarding the long-term integrity of your vehicle's essential cooling system.

Regards
D.

BMR_LVR · Mar 7, 2011

Owww ..... my brain hurts after reading that. You guys are way above my head. Thanks for the summary though.

Steve

ricks5series · Mar 7, 2011

You too Steve, I read it twice and will probably read it again tomorrow, lol. Love this kind of stuff.

robertobaggio20 · Mar 7, 2011

D, thank you for your response. I'll reply to it later tonight. However, I have an interlocutory question.

You mentioned sacrificial anodic protection on ships using sacrificial zinc anodes, which will rust away in preference to the ship's hull due to their higher electrovalence or 'reactivity'....can something like that work on our cars? If so, how would it be constructed...can you conceptualise it aloud? Rust can be a problem on 20 yr old vehicles as we all know. Thank you.

ricks5series · Mar 8, 2011

Roberto,
I have seen sacrificial zinc anodes attached to the radiator caps of Ford F-150 trucks. Perhaps you can look on the internet for a generic one that we can utilize?

P.S. Still dealing with this vanos unit, lol.

DnA Diesel · Mar 8, 2011

Roberto, not sure if it would work the same way as on ships. I have, however, heard of ionic anti-corrosion systems that are electrically powered. Can't recall the brand name, but many municipalities in the northern US and Canada use them on their fleets. Probably working on a similar principle.

cheers
D.

bluebee · Apr 2, 2011

For the record, yet another brave soul took the propanol plunge today:
- Changed OEM coolant for Evans NPG+, by aioros ('99 528i)
- I did it! A zero pressure cooling system, by chiefwej (2003 540i/6 //m-tech)
- Evans NPG+ Waterless Coolant --anyone use in a v8?
- Evans Coolant. Anybody use it?

Here are the current recommendations I can cull from the record (still needs improvement, probably a LOT of improvement ... but it is what it is):

E39 Engine coolant: phosphate free (for Europe's high-mineral-content water), amine & nitrite/nitrate free (for USA long-life requirements), & low-silicate or silicate free (for Japan requirements) 50:50 mixture of ethylene glycol & water (the Bentleys say distilled water (Bentley 020-11), aka de-mineralized or de-ionized water, some call it purified water, and the BMW AG TIS 12.11.2007 18:56 specifies water with a pH from 6.5 to 8.0, maximum total hardness of 3.6 mmol Ca++/liter, maximum chloride content 100 mg/liter, and maximum sulphate content 100mg/liter; interestingly the BMW TIS says "potable tap water usually fulfills these requirements". EPA reports show San Jose & NYC tap water easily fulfill these requirements. The BMW TIS expressly states additives are not helpful and are not recommended. BMW lists a score of recommended coolants in their BMW AG TIS 12.11.2007 18:55 which meet the BMW N 600 69.0 standard, some of which are BMW PN:81.22.9.407.454 1.5-liter; BMW PN:88.88.6.900.316 1 gallon; Castrol Anti-Freeze NF; BASF Glysantin Protect Plus G48, & Havoline AFC (BD04); but most of which are not easily found in the USA. Many Bimmerfesters recommend BMW coolant; however other Bimmerfesters recommend Prestone Extended Life 5/150, Valvoline Zerex G-05, and Service Pro Universal Formula. Others (e.g., chiefwej, aioros), recommend Evans NPG+ but be aware propanol entails a different maintenance philosophy than the aqueous fluids listed above and is not compatible with them. [Total Volume: 1997 I6=10.5 quarts (2.6 gallons), 1997 V8=12.0 quarts (3.0 gallons), 1998-2002 I6=11.1 quarts (2.8 gallons), 1998-2002 V8=12.7 quarts (3.2 gallons), 1997-2002 V8 with latent heater=13.5 quarts (3.4 gallons)]. Prestone says the only reason for phosphate free is the extremely high mineral content of water in Europe - and that in the USA, it's not needed. Replacement Interval: Every three years (Bentley page 020-9) or every four years (aforementioned BMW AG TIS) starting from date of manufacture (except for M-Power vehicles which have 3-year intervals). Note: Mixing BMW-recommended coolant brands is permissible; but mixing types is not permissible unless it's an emergency.

http://www.bimmerfest.com/forums/showthread.php?p=4386547#post4386547

And, here's what we have for the pressure cap:
- Solution to Exploding radiators (30psi/2.0bar pressure cap -> 20psi/1.4bar)

And, for the 'typical' coolant, these are useful:
- The truth about Coolants
- What Coolant you using?
- Best coolent to use for my e39??

And, for all BMW E39 fluids:
- DIY Glovebox & Bentley supplement: 1-page summary of the dozen recommended E39 fluids

bluebee · Mar 27, 2013

For the crosslinked record, this was asked today:

Guam135i said:
Newbie question what is npg?

I tried to put all the abbreviations used in the E39 forum over here:
- BMW E39 technoterms, acronyms, glossary, definitions slang, technical terms, abbreviations (1)
But, interestingly, even though I spent perhaps 100 hours on that one thread, I didn't list NPG unfortunately - so you wouldn't have found it there.

Luckily, the bestlinks has everything you need at the touch of a keyboard.
Typing /npg F3 in the best links, for example, netted this:
- A picture of every failed part in the cooling system (1) & various techniques to properly bleed (1) (2) (3) & refill (1) & drain (1) (2) & flush (1) & what coolant to use (1) & all about propanol-based zero-pressure fluids like NPG+ (1) (2) (3) (4) (5)

Clicking on those five threads, we find out this about NPG:

robertobaggio20 said:
8. There's a company called Evans that sells a zero pressure cooling fluid called NPG+ (this is a brand name). Its basically 100% propanol which (if i'm not wrong) is an isomer of ethyl glycol, and is thus non-aqueous i.e. does not involve any water. .

chiefwej said:
Well, I decided that if I run a zero pressure cooling system, I may not have to do that next cooling system overhaul. No pressure, no exploding radiator.

So I ordered a case of Evans NPG+ waterless coolant. Not cheap at about $120, but if it saves an overhaul............... The case was 4 gallons. It took 12 liters (or about 2 3/4 gallons) to fill the system. That leaves over a gallon for top-ups, since you can't add water or any other kind of coolant with Evans.

I fully drained the system, radiator, lower hose, block drains, and ran the heater pump to get it out of there. I must have got it all because Bentley says it holds 12 liters and that is exactly what I got in it. So everything must have been out and there can't be any air trapped in there. After the NPG+ fill I changed the 2 bar cap for a 1.4 bar one.

With a boiling point of 375 degrees there should never be any pressure in the system now.

bobdmac said:
Bluebee, the short version is that the Evans boiling point of 375 F means that the cooling system doesn't need to be pressurized to keep the coolant from turning into vapor (boiling) before it gets to the radiator to cool back down to operating temperature.

As aloros said, this means that the vulnerable plastic parts and hoses don't have the added problem of handling elevated internal pressures.

So, given that I always try to put the answer to a question in the most likely place others will look for it, I'll add the following short description to the acronyms list:

NPG = A high boiling point (375°F) waterless (ethylene glycol based) coolant used to keep pressures in the cooling system close to zero bar (aka Evans NPG+)

http://youtu.be/t7PykrgzWPQ

BMWFatherFigure · Mar 27, 2013

Low / no phosphate coolant is needed in ali BMW's to prevent the deposit of ali phosphate on the inside of the rad tubes. Ali phosphate is an insulator so prevents the rad from working. In temperate zones with a good cooling system no pressurization is necessary. I ran my R50 Cooper and a Suzuki Alto for years with out any pressure but full flow to the standard expansion tank. Maybe some one can find a way to remove phosphate without eroding the base metal.

amexjoe · Dec 7, 2013

do i really need to drain and refill

great post !!!
ok last week all the coolant went bye bye in the 09/94 530i (upper rad hose popped off)
i dumped in 2 x 3.79l of the stp universal concentrate and 3l of 50/50 stp universal.
the plan was to get the bmr home then put in the good stuff.
so...
do i need to toss out the stp and get the zerex g05?

Dereke34 · Sep 28, 2014

Has anyone ever used a light mixture of white vinegar and distilled water to flush there coolant systems? I've done this in the passed with my old motorcycle and my dad's old truck. But fill with a 30%ish vinegar 70% distilled water. Fill the coolant system completely and run until the thermostat and everything opens. And then let it sit over night.(obviously don't want to do this in the winter). The next day run the engine until operating temp and then get ready to see some junk come out of your engine! After that repeat with a 100% distilled water solution to flush the vinegar out and more junk. Then fill with 50/50. And enjoy a cleaner cooling system.

BMWFatherFigure · Sep 29, 2014

Mild acid - way to go...

jimmk · Apr 11, 2015

waterless coolant

One member said that the cooling system manages the temperature, and that a coolant like Evans would not make the car run cooler, also he mentioned that the engine is designed to run at a specific temp.
My point is Evans will get just as hot as the system requires ; however it will not boil, thus keeping pressure in the system down and that should be a good thing, if the coolant does not boil regulating cooling throughout the engine should be more consistent. When coolant boils it is forced away from the surfaces to be cooled by the bubbles generated while boiling Evans will reach 316 degree F before boiling. About lower pressure, I believe that lower pressure and the absence of oxygen(present in water) will result in longer life of all cooling components especially radiator and radiator hoses. EXAMPLE: BMW runs nitrogen in the tires because for one nitrogen does not oxidize the rubber like oxygen does.

jimmk · Apr 11, 2015

I wish to start using "Evans Waterless" need input.

MeNoo · Apr 11, 2015

I'm about to be very harsh, but this is my opinion (mixed with the occasional fact) about it. Guess I felt like crushing your dreams. My bad.

1. Thread from the dead.

2. Your coolant doesn't boil (scientifically impossible in a sealed unit) unless overheating, at which point your coolant cap has blown and you need to worry about other things than what coolant you were using.

3. The parts would in theory have a longer lifetime, but most have to be replaced because of different wear and tear than internal.

4. The reason you run nitrogen in a tire is because it doesn't raise and lower pressure with temperature as much as oxygen, especially humid oxygen from a compressor. IE; you can use the tires (in a racing environment) in a wider range of temps with better performance.

EDIT: If you properly maintain your cooling system, you don't need to worry about it.

MySatinDoll · Apr 11, 2015

Dead thread from a member (not you MeNoo) who lost his crediability and gave dangerous advise revived.
MODS delete this thread please.

MeNoo · Apr 11, 2015

I didn't mean to dig that up, didn't realize...

MySatinDoll · Apr 11, 2015

No your question is OK. It shed light to the unspoken rule. Unless the information is textbook, common knowledge or the author states otherwise. Use the information at your discrestion and continue to research the info till its golden in your mind or to your circumstance.

MeNoo · Apr 13, 2015

Hey, you can't over-change fluids...

TheEinstein · Apr 13, 2015

My $.02...

I've kicked the idea of using Evans around. I suppose my biggest interest would be the reduced internal pressure for all them plastic parts. Heat cycles are rough, but expansion pressure is nothing to omit as far as wear will be concerned. And as long as that plastic is designed to last, it cannot last forever being subjected to such. Another mildly interesting factor is "lifetime." Thats a tough one to beat, since supposing all goes to plan, you will never need to flush or check it again.

As touched on, I came up with a no-win scenario or two.
1) It's expensive at cost, and equally unavailable locally so far as I've looked in many cases. Take a long drive into the mountains and by some chance rip a motor mount, chewing a hole in a radiator hose, now what? Tow it? It doesn't have to be a failure of a cooling system component for the vehicle to dump that gold and diamond enfused liquid (disclaimer: it's not gold and diamond enfused) right onto the ground. Can you imagine, even a small leak, far enough from home, that gets bad enough where you cannot drive it back. If it were ordinary coolant a gallon of distilled water or even a hose from some farm house could get you home, but since that stuff is in there, you may as well be on the moon. Now, again, you're towing, instead of topping up with some plain old water. Closing this scenario, where will you source it in a pinch? If you were by some miracle able to source it, at what "luxury tax" cost? Better believe it's not gonna be at cost, and how much cost does it take to outweigh future flush and fill jobs?

2) This one is simple. Again back to any nature of failure to the system. Lets say you were the smarter sort of person, and you keep a full jug with you at all times, plus maybe a jug in reserve at home should you ever need it. Good piece of mind, but again, out of reach if you are not so near it when the need arises. But lets say, you're forced to fix on the side of the road, and you use all of what you have with you. And it wasn't enough, now what?

My simpler point, if you're Jay Leno, you are not gonna be stranded, and towing the car is MOST likely his desired option. If you're an average guy, stretching a dollar in this case, or just thinking of staying ahead, one could really get themselves into a pickle given you CANNOT just add water.

I'm sure we probably all can see my points without me having pointed it out so directly, but since we're talking about it...

MeNoo · Apr 13, 2015

No, anti-rust is still important. There are still non-aluminium blocks, and aluminium (although it doesn't rust in a traditional sense) still oxidizes. Besides, what's an anion have to do with it? That just means an ion with a positive charge. I believe, off memory, water is literally part of the equation in oxidization. That said, like you stated, a week of tap water won't do enough to notice, especially if you are changing the water. Back to Evans as a non-viable coolant, my car is too needy to have a coolant that expensive. I KNOW it will need a repair or service in the coolant loop the day I put that coolant in.

paul1733 · Apr 14, 2015

Gonna touch wood, there we go.
Been driving mine since December 2008, the mechanic who fixed the car when i bought it with a busted timing belt used this coolant but i know he made a lower mix ratio cause he's a mechanic & i had to replace the head gasket myself in September 2010. The bottle has 3 mix ratios on it, the lowest being for minus 20°C & we would be lucky to get below 0°C in perth, but over 40°C no worries. Anyhow when i did the head gasket the only thing i replaced was the timing belt, so all the original coolant hoses, thermostat, heater hoses & radiator that were all replaced during the mechanics repair in 2008 are still on there. I haven't had to top up coolant, had overheating issues or heater not heating. This will be a 27yr old car in september, it may have only done 130k miles (bought it with about 65k miles) but dang there are things i wont substitute coolant & brake pads. The genuine BMW brake pads have been on since the repair in 2008, 7.5yrs 65k miles still going no squelling & brake like new at nearly $400 a pair well worth it.
Thats my $0.02.

The truth about Coolants

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