The spec is non-phosphate ETHYLENE glycol, and has been the spec since
Mercedes started putting aluminum heads on cast iron blocks post WWII.
Propylene glycol has not been approved by any manufacturer I know of,
certainly not by any of the Euro manufacturers. Stick with the specs, or
experiment at your peril.

Note that the cheap green phosphate loaded standard ethylene glycol also
states "safe for aluminum". It's a lie as regards European metallurgical
testing by all the manufacturers from Mercedes to Jaguar, and including VW
watercooled.

At 07:42 AM 08/09/2003, you wrote:

>I am using the Prestone Low Tox brand coolant (propylene glycol) - it's the
>one that's less toxic to dogs and cats. I may be wrong but my understanding
>is that this brand is phosphate free and the color is green. The auto parts
>store folks assure me it is phosphate free and the container states it
>protects alum heads - if anyone has different info I'd sure like to hear
>about it. Joe