coolant info from Mike Focke's web site:
Porsche claims their coolant is Lifetime, but don't believe it. It is simply a silicate and phosphate free Glycol based coolant. This should be changed every 5 years/150k mi. (whichever comes 1st) in order to provide maximum corrosion protection. It is the organic carboxylates which breakdown after this interval.
Instead of buying the super-expensive Porsche Coolant from the dealer, Zerex Extreme Life 5/150, Texaco Extended Life, Shell Rotella® ELC Extended Life Coolant, UNI-GARD 5/150, Mercury Extended Life Coolant Anti-Freeze, all meet or exceed Porsche Coolant requirements and are much cheaper. Use of any other type coolant is not compatible with the system and can form a gel-like substance if mixed with the proper coolant which can then obstruct flow, create hotspots, blow up your engine, etc.
Mike Focke's antifreeze
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