Coolant and yes I have searched and read

[mikefocke]

Organic acid technology

wikipedia is a good place to start.

[Pdwight]

This sums it up better than I have seen it in one place before

[BrokenLinkage]

OK I'll bite:
@ Markus
1) why did Porsche use O.A.T.?
2) where did you get the equivalent-to-Porsche-brand fluid? Is there a compatible and comparable alternative to purchasing fluid from the dealer?
Thx

[Lew]

Pentosin's PENTOFROST. It's label states it's for VW's, Audi's, and Porsche's.....and all aluminum engines.....