I'm surprised this is the first reprimand I have received on here for not using the BMW coolant [grin]. So, all the other vehicles I have run for decades (some up to 300K miles with the original water pump) on the Prestone stuff did not have protection for the water pump and radiator? And how can you know that is what ruined your system, and that the same would not have happened while running the BMW coolant?

As far as I can tell, the radiator is made of aluminum, the block of cast iron, and the water pump I imagine of materials not too terribly different from all the other vehicles I have run. So, what sort of protection is needed here that is not required for so many non-BMW vehicles?

I'm not arguing so much as I am curious about what it really is that justifies the concern. I currently have the BMW suv, 3 GM vehicles, and a Toyota Prius (for which Toyota's own special coolant is spec'd). This means I'm supposed to be running 3 different types of coolants (and I am, but it is the Prestone I have in the BMW right now). I just have to wonder how necessary it is. Or, if the BMW coolant is so great, why am I not using it in all my cars? I do stay away from generic or "off-brands", but Prestone says their stuff will protect my stuff. Are they lying?

JCL: Yes, that did occur to me about the accuracy of the tester. Thinking I'll go back out to the garage soon and repeat my experiment with the Prestone coolant, see if I get the same reading.

X5Cat:

Actually, the radiator is made of aluminum and PLASTIC. It's the plastic that's the problem.

The BMW antifreeze supposedly doesn't degrade the plastic as fast as the other stuff, but go ahead and use whatever you want to, it's your X5. :thumbup:

Same as all the other vehicles I have, unless it's a unique blend of plastic. But again, I'm more curious about the truth than just wanting to argue about it. Does it mean I'd be ahead to run BMW coolant in all my cars. Or does their stuff protect "their plastic" better? Would be curious to know what Prestone would say in their defense.

Use ONLY BMW anti-phosphate, anti-amine, anti-phosphorous coolant! Do NOT use regular store bought coolant, which typically contains ethylene glycol and doesn't correspond with the specifications of an BMWi cooling system.

Poor quality coolant contaminates the system and eats away at metal, rubber, and plastic components. Obvious external indicators are bulging coolant hoses and white calcified residue oozing from coolant hose clamp mating areas. Not so obvious is lime and scale deposits that begin to build-up in the radiator core, restricting coolant flow and causing the engine to run hotter (especially in summer and warmer climates). All of this eventually causes serious engine problems (i.e. water pump failure). If your coolant is green or brown in color, thoroughly flush your cooling system immediately! You'll notice similar warnings in your owner's manual under the coolant section.

Here's a pic as to what may happen if you use the wrong type of antifreeze.

http://www.blauparts.com/assets/wrong_audi_coolant.jpg

Your block is made of aluminum. Your pump is a combo of steel, aluminum and bronze. The additives in the coolant are specific to the manufacturer because of the materials they use for the gaskets, hoses, engine block, and cooling system parts, as well as the intended operating temperature/pressure range for the coolant. Yes you can use any coolant you want, but you are likely to develop leaks sooner with the non-BMW coolant. Overfilling your expansion tank is typically the most common cause for early leaks though.

Note: Don't use tap water for mixing!

If you regularly have temperatures that cold every winter, I recommend a block heater or coolant heater as you are nearing the limits of new oil (depending on grade), used oil likely has a higher pour point temperature. 5w-xx good to -40F and 10w-xx good to -20F.

Now on my 4th BMW, I have never used anything but BMW branded antifreeze. With other vehicles, I was quick to switch to extended life coolants [for example, Cat ELC in Ford diesel trucks], but, with bimmers, like benzes and [I understand] Hondas, you pays your money and takes your chances using aftermarket coolants .....

The BMW coolant and gallon jug of distilled water costs around $25, makes 2 gallons.

There's not much savings in running non-BMW specific coolant.

Why would anyone do it?

Availability of the BMW coolant if not living near a dealer.

BMW coolant is carried online by RealOEM, BavAuto, Turner M'sport, Tischer, Pelican Parts........

Sorry, I was just trying to think of a reason someone would need it and not be able to get it right away. I agree, if you are ordering cooling system parts for a repair or maintenance, you should be buying the coolant at the same time.