I got an engine that has some funny CVVT seals that will shrink with pretty much any ILSAC motor oil, and then the engine will rattle at startup. If I use an A3/B4 oil, they seem to shrink less, so there is less drainage when the engine is off, especially in winter. If I use Mobil 1 EP High Mileage 5W-30 (it calls for 5W-30 or 5W-40), there is no drainage, as I never hear it rattle at startup, regardless if it's summer or winter.
I guess my question is: what else is special (or different when compared to regular add packs) about a "High Mileage" additive package, beside the seal swellers? Thank you.