BimmerFest BMW Forum banner

what is the best anti freeze/coolant for 1991 525i?

13K views 27 replies 10 participants last post by  paperplane94 
#1 ·
putting in a new radiator pipes and all, what is the recommended coolant for the car?
 
#3 ·
My best suggestion is for you to use cheap, walmart coolant for your car of any brand, provided it is brightly coloured and has a strong smell. Coolant technology has evolved and the differences between them are usually not significant for our cars. I've not noticed anyone having any problems specifically traceable to the brand of coolant that they use. Secondly, bright coolant makes leak detection much easier. The oem coolant is faint blue in colour and not useful here. Thirdly, if any coolant hose ruptures while driving, a the strong coolant's smell will invade the cabin and give you early warning of trouble, long before the engine actually overheats. Our car does not have an overheat alarm so having this facility is very nice. The OEM coolant practically has no smell. This aspect proved useful for me personally on two different occasions nearly 2 years ago.

Use any brand name if you prefer but see to it that it is brightly coloured (luminescent is best) and strong smelling. And keep an extra can of concentrate in the car.

Recently, I read about redline's water wetter over here. It is better than a coolant/water mixture in terms of heat transfer and average overall temperatures. I've just flushed my radiator and dumped a bottle of it in. The observation process is in progress in earnest. :)


rgds,
Roberto
 
#4 ·
Why not just use BMW coolant? I've been using it the whole time I've had my car.

It's almost impossible to not notice if a rad hose blows anyway. Plus, BMW blue is odorless, so every time you turn on your heater you won't smell the stench of Prestone.

I'm not in anyway saying Prestone is a bad product, I'm saying, why not use the coolant that was actually designed for a BMW, the car you spend hundreds on and, eventually start to love?

Just a thought.
 
#5 · (Edited)
Why not just use BMW coolant? I've been using it the whole time I've had my car.

It's almost impossible to not notice if a rad hose blows anyway. Plus, BMW blue is odorless, so every time you turn on your heater you won't smell the stench of Prestone.

I'm not in anyway saying Prestone is a bad product, I'm saying, why not use the coolant that was actually designed for a BMW, the car you spend hundreds on and, eventually start to love?

Just a thought.
That's a good point Costa. This is how I look at it.

I agree that it is impossible not to notice when a hose ruptures, but if this happens while driving, you will not be alerted to the situation except by an overheated engine. Engine overheats need not destroy the car but they are to be avoided wherever possible for obvious reasons. With a coolant that has a strong odour the situation is different. A burst hose sprays coolant in the engine everywhere. Air that enters the cabin gets sucked in through the engine in some way. So, the strong smell of the coolant that is now spewing everywhere, also gets carried into the cabin. You will instantly notice this and then begin taking action to stop the car and check. This usually does happen before the engine begins to overheat....you need to lose a fair bit of coolant before overheating takes place, although of course this can happen in 5 minutes as well depending on how bad the rupture is.

Secondly, some burst hoses are not severe. You might not notice it in a casual inspection. However, when left unfixed, a small rupture can suddenly turn into a big one and become a showstopper. With a strongly smelling coolant, you will smell the leak even if it is a small one, and then begin to check everything more thoroughly. It is a great warning device.

The reason why BMW does not have a strong smell in their coolants is because they do not design the coolants for E34s, but for their latest cars, where the probability of hoses rupturing is rather low because the cars are not as old as ours, and also because they now have all kinds of warning systems to alert the driver to pressure drops in the cooling system.

Then we come to the question of coolant itself. Is cheap coolant worse than OEM coolant ? Well, it is fairly clear that nothing can go wrong with OEM coolant. That being said, the complex elements of coolant chemistry are in the "bouncing the rubble" category of life for our car. Any modern coolant being sold in the market will do the job as well as any other, and certainly brand name coolants would have no issues. Any exceptional coolant will probably not give you any benefits that are worth having or can be felt, practically speaking. I wouldn't trade my normal coolant with a strong smell and bright colours for an exceptional odourless coolant. That smell and bright colours sir is important, in my experience, when you're driving an old car and especially when you're the person looking after it primarily.

You should not be smelling prestone in your cabin if everything is fine. I do not smell my cheap $3.50 coolant concentrate in my cabin, and I've had to replace practically everything related to the hoses etc in my car. So, if you are smelling any kind of coolant in your cabin, and if you have properly washed off any spilled coolant after you topped up your radiator, I would say that you need to look for any small leaks somewhere, or perhaps tighten up some hose clamps or something. Please open your hood in a windless area, and begin sniffing. Do you smell prestone? If you do, you really should find out why. In any case, check to see all hose fittings are tight and inspect hoses as best as you can. Hoses that are hard are prone to cracks (major or minor) so those need to be checked more carefully and replaced if a suitable opportunity arises naturally. You rad cap and bleed screw ought to be new - since they cost less than $15 in total.

cheers,
Roberto
 
#7 ·
Well well, interestingly, I flushed my radiator and dumped in redline's water wetter yesterday. While driving today, guess what ? I noticed an odd smell in the cabin. Stopped the car and took a quick look. Drip drip drip...coolant was dripping from the main radiator hose....one drop every 10 seconds, and that's at high pressure so its not much.. Looks like I didn't tighten it up properly. Tightened the hose clamp, rinsed off the excess coolant and went on my way. No further smells after that. Stopped later and checked again. No drips.

I'm glad to use a coolant that has a strong smell. You can use BMW coolant if you like. I'm sure if a small leak springs somewhere, you will just feel it in your funny bone, or you car will be polite to hold its water until you reach home and then dump it all on the garage floor so that you can see it clearly. :)
 
#11 ·
I use OEM. If you inadvertently use a high phosphate coolant it will stuff up your radiator (given time). For me OEM works very well.
 
#15 ·
Well son, I do happen to own an e34, my sixth BMW in my driving career. I try to work my character assisinations into my factual replies, I think it adds a nice bit of humor especially when having to reply to your rediculous posts.

What happened to your lobbyist thread bobby? Was it just too stupid to stay? I thought so.
 
#17 ·
I checked out the 'phosphate' info from Prestone. They state that phosphate is of no concern in the USA because the water is better. I first read about he phosphate problem in a BMW CCA publication. I'm sticking with OEM.
 
#20 ·
Is it seriously being put forward that prestone or wal mart coolant would be better for the car than the coolant the manufacturer specifies?

The question was, "what is the best", not what is cheaper, or greener or stinkier.
 
#21 ·
Just to qualify my 'phosphate' response - I refer you all to 'BMW Enthusiast's Companion'. Bentley Stock number: GBCC. ISBN: 0-8376-0321-8. Page 81. No point in re-inventing the wheel, just following the steps of wiser men. Just use distilled water to fault find! Cheaper than coolant.
 
#22 ·
The only flaw being, bobby believes he is the wiser man:dunno:

The above post is correct though. BMW is far more qualified to spec coolants for their engines than even prestone. Simply easy cost effective, I agree, no reason to re-invent the wheel.
 
#25 ·
I use Prestone 50/50 in all my cars never had a problem (Volvo now has 260,000 miles). Your car does not know the difference, though I respect those who feel they must use manufacturer products, such as BMW oils/coolant. As the argument goes, engines rarely fail on oil type or coolant type, the flow systems are what fails.
 
#26 ·
Just to be clear I use Castrol oils (grade dependent on vehicle) changed at half indicated intervals, genuine coolant and PBR (Australian brand) DOT4 brake fluid changed on BMW intervals. To paraphrase the article (no author) Behr radiators supplied in the USA are prone to AlPO4 (phosphate) coating on the radiator tubes, if the wrong coolant is used. The author also thinks that the standard radiator is on the small side across the range. The BMW coolant is termed G-48 (which means nothing to me; maybe some one else knows). Behr know AlPO4 is an insulator and will cause overheating problems. Brass is not affected. IMO radiator flush compounds do not seem capable of removing the AlPO4 coating. I GUESS that anything that will dissolve the coating will also dissolve the radiator with it, but that is a GUESS. Any chemists out there??
 
#27 · (Edited)
AlPO4 is aluminium phosphate. Some investigative searching and deductive reason (surely not what I'm infamous for) brought me to the following potentially insightful article :

http://www.ehow.com/how_8442658_remove-aluminum-phosphate-aquariums.html

I believe most phosphates are too stable to be removed except by scrapping them off.

Cummins sells a hard core radiator flush. Perhaps it is time to check that out and see if they will sell it to the general public:

http://www.cumminsfiltration.com/pdfs/product_lit/emea_brochures/LI33024-GB.pdf
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top