I have ' 92 SL2 since new with 120K on it now. It does use some oil but nothing yet to be concerned about between 4K oil changes. Currently am using 10w30 as I always have. I have access to good quality bulk oil in two grades, either 10w40 or 15w40.
It seems in past postings I have read, NOT to use 10w40 in newer modern engines. I don't have a problem with the 15w40, but could someone explain the reasoning for the 10w40 issues, if any at all. Everyone's opinion are appreciated.
Thanks, James
THe reason that 10w40 is not approved in modern engine is because a large amount of VI (Viscocity Improver) is need in conventail oil to give it that range. VI tends to cook out of oil in piston ring area with time and cause them to stick if not changed frequently. 15w40 does not have this problem. GM had boatloads of stuck ring problems in
80's that lead them to no longer approve 10w40.----------------- TheSnoMan.com
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