Originally Posted By: addyguy
I think in this day and age of severe fuel dilution in small, high-strung engines STP is just the thing to bring oil back to 'where its supposed to be'.
One possible problem with that: STP used Group I or II base oils, prone to oxidation in high-strung engines, and the VII chemicals in there have been said to be low-quality types as well. This could lead to extra piston deposits and varnish. Using just a little in a well-formulated full synthetic oil shouldn't be a problem since it'll mix with the oil's powerful anti-oxidant package and dispersants. .... I think.
Instead, amazon order some Schaeffers Moly E.P. Oil Treatment, at KV100=238 cSt, its thick and likely has better components. It contains antimony and organic components, with very little other unnecessary stuff. Thickener for sure.