" From: Brien Tourville <hh7x@xxxxxxxxxxx> " " there's been an oil thread over on the strokers list. if you're " trying to protect your older engine from cam wear and failure, what it " comes down to is zinc and phosphorus levels; they've been reduced as " they slowly poison catalysts, and modern roller tappet valvetrains " don't need it anyway. [maybe cause and effect?] the article kyung " linked to is especially enlightening; the old zinc phosphate levels " were apparently set from research published in a 1977 sae paper it " mentions. " " in short, what most of us want to look for is an API rating of SG, SH, " SI, or if necessary CI. or add a can of GM EOS with every change. " " " " === . === " " " " All other ratings for the ZDDP package are " defunct - no longer applicable other than CI-4. how do you mean? the page at lnengineering clearly lists a mobil 1 that's SG rated, and refers to another mobil 1 'high mileage' that's SI. current oil rated CJ or SM does have only a fraction of the ZDDP earlier ratings carried. " The new API CI-4 rating for the ZDDP package " is only in Mobil 1 Truck & SUV / DELVAC " or Shell Rotella T. of course - C means 'compression', eg. diesel. those are diesel oils. " BMW OIL - is relabled Mobil 1 DELVAC - and used in " BMW cars - trucks - motorcycles. the hitch with this stuff is that afaik it's only available in 15w40, a little on the thick side for most parts of the country. " The only reason it will 'slowly poison' catacytics is if " your engine is BURNING OIL. all engines leak a little oil out the tailpipe. maybe under normal circumstances the poisoning is so slow the cat succumbs to other things first... it's academic to us older amc drivers anyway. ________________________________________________________________________ Andrew Hay the genius nature internet rambler is to see what all have seen adh@xxxxxxxxxxxxxxxxx and think what none thought _______________________________________________ Amc-list mailing list Amc-list@xxxxxxxxxxxx http://www.amc-list.com/mailman/listinfo/amc-list