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Really confusing that the Bentley Manualwould say that when replacing the coolant for BMW Z3s that a 50/50 mixture of water and coolant should be use. Even the Bavarian video on replacing the coolant says to use the 50/50 mix, but in the same video they show the Evanswaterless coolant. The manufacture, BMW recommends flushing/replacing the coolant (BLUE coolant) every 2 years to prevent rust buildup and read somewhere that the WATER was problematic with water pump issues. So when is it OK to use waterless ??? :dunno:
 

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I looked into going waterless a while back. A lot of e39 guys have tried and found negative results with high temp and efficiency.

I opted to stick with mixing blue with h2o. If it isn***8217;t broke don***8217;t fix it. Just my two pennies.
 

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The waterless stuff is an option, but you have to somehow remove all the water from the system before you switch to it (good luck with that). I never thought much about it, maybe if you have a race car or something it might be worth looking into. My thought was, what if you're somewhere and have to add coolant? With normal coolant you could just add some distilled water, but you can't mix water with the Evans stuff, so... I don't know, I just use the BMW stuff (which is really good) mixed with distilled water 50/50. Don't use tap water...

The reason to replace it every few years is the protective additives in the coolant eventually wear out and then corrosion can start to happen in the system (like the aluminum engine), so then the coolant could become a path for stray electrical currents, which then could help further corrode things through electrolysis, etc.

I haven't heard anything about water hurting the water pump... Some people in hot climates run straight distilled water (water actually is better for cooling than coolant/antifreeze) with an additive like Redline Water Wetter but this would be a really bad idea if you were ever caught in freezing conditions. Also, one of the functions of the coolant is to lubricate the water pump, so I would want to make sure the Water Wetter could serve that purpose.

Anyway long story short, I think your best bet is to use the BMW stuff and distilled water 50/50.
 

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Well, sometimes you just don't know what to believe, in the fact that one site will have negative things from an individual having an ax to grind about a particular product or business. I like to stick to the Bentley Bible and the success stories from members of tried and true results. BTW........my coolant is green, and have not had any overheating problems...........is that OK?? Did not have any previous maintenance history to go by.
 

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I'd get it out of there (the green stuff). The only thing 'not overheating' tells you is that you don't have air bubble problems. Bigger issue is that your (and my) engines are aluminum, and some of those other non-BMW antifreezes have phosphates or something like that which corrodes the aluminum. For a long time you really NEEDED to use the blue BMW stuff to protect your engine. Now, I think it's ok to use certain other ones but I don't know which (RF900rkw on the other forum has talked about that). But if you don't know for sure what is in there now I'd get it out and replace it with the BMW stuff asap.

Remember to drain from the block plug as well as the radiator to get as much of the old stuff as you can. Some will be left no matter what you do. I would drain as much as I could from both plugs (jacking up the opposite corner of the car to help it drain more), do a fill with just distilled water, drive/idle the engine for a short while until warmed up to get it circulated, then drain again. Then fill with the BMW fluid/distilled water mix.

Make sure you do some research on properly filling/bleeding the cooling system on these cars... If not done properly, air in the system can cause overheating which will damage the engine (since it's aluminum). I use an Airlift vacuum fill device to help drain out more remnants of fluid after the initial draining, and especially to help fill without as much air issues.
 

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Well, sometimes you just don't know what to believe, in the fact that one site will have negative things from an individual having an ax to grind about a particular product or business. I like to stick to the Bentley Bible and the success stories from members of tried and true results. BTW........my coolant is green, and have not had any overheating problems...........is that OK?? Did not have any previous maintenance history to go by.

It***8217;s not going to cause an issue overnight all of a sudden. As long as it***8217;s clean you should not worry every mile. With that being said, the bmw fluid is recommended for the system***8217;s components. Because you don***8217;t know the quality or grade of coolant you have in yours, you might as well change it back to the ***8220;correct***8221; stuff when you get the chance. Of course, as stated by others,mix 50:50 with distilled not tap water.
 

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The blue BMW coolant is not much more expensive than green coolant, particularly when spread over 2-3 years, so I use that. BMW did a lot of research and experimentation to determine that it works well with their materials. In fact, it seems like every OEM recommends their own coolant and warns to only use theirs. I have special coolants in my garage for GM, Honda, BMW, and John Deere. Again, none of them are particularly expensive.

Waterless coolant is a specialty item best suited for vintage and rare cars. Since it does not have water, it does not corrode. Nor does it boil, so it doesn't need a pressure cap, thereby reducing the pressure on fragile cooling system components. Unfortunately, it does not transfer heat nearly as well as water-based coolants leading to higher engine temperatures. That's acceptable for an iron engine, but is risky for an aluminum one.

Water-based coolants remain the best balance for transferring heat out of the engine (which water is best for) and eliminating corrosion, cavitation, contaminants, etc., (which the [blue] additive is best for).
 

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Sorry, had to re register for what reason, I don't know. Was Z3 freak, but now Z3 slead, anyway I understand that the M motors have the cast iron blocks, so they would probably be using the waterless coolant. After my purchase of the Z3 last year, I did notice a white substance around the upper hose going into the radiator and around the cap of the expansion tank. My guess the PO had the car running hot...........
 
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