Sierra is not phosphate free. The advertisement of being so is legal, but only
because it can be drawing a figured comparison against an ordinary antifreeze.
Sierra has about 3 to 5% phosphate in it.

When I found this out I felt gypped, and went back to VW $11 a gallon... Call
the company, and always ask the advise of good parts/service guys, especially @
VW. They'll of course say use their product, but baring everything else, use
their coolant!

AB

Jfp w/3 WBXs wrote:

> Hi List,
>
> Recently, for my next WBX coolant service, I decided to try Sierra
> phosphate-free coolant instead of my usual Autobahn @ 11 bucks a gallon.
> My question deals with the expansion characteristics of Sierra coolant. The
> Sierra coolant seems to expand 2 or 3 times what the Autobahn does. When
> cold the Autobahn starts at the minimum line on the expansion tank and rises
> to below the maximum line at full hot. The Sierra also starts at the min
> line but rises to well above the max line(into the screw cap area) at hot
> idle with the aux fan on. The cooling system is functioning properly and has
> been bled correctly. It seems that the Sierra coolant just expands much more
> than the previous Autobahn. Anyone have experience with the cold-to-hot
> expansion behavior of phosphate-free coolants.
>
> Regards,        John
>
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