I've seen a couple of sites now who have tested the wear protection for Mobil 1 5w30 and Mobil 1 5w30 Extended Performance, and the numbers are quite different between the two: 118,000 PSI for the M1 5w30 and just 86,000 PSI for the Extended Performance variety. M1 promotes the EP product as everything the same but better than the standard M1, but if there is this much difference in their wear protection than I don't want to use the EP variant. I won't even quite go up to 10k miles let alone 15k miles per oil change, but for example the back of the bottle shows the EP offering better protection for high-temperature engines. I asked Mobil about this and they said it was b/c the EP is slightly more resistant to break down and has a higher quantity of additives to allow it to handle the heat a little beter. Okay, great. If EP is everything the same as the standard M1 but only better, I want to run it in my Dad's Cadillac CTS V-Sport with twin turbos and that big timing chain, as well my wife's Lincoln with the 2.0L turbo four citing the better engine heat protection, (both are GM and Ford spec rated, as well as Honda HTO-06 which specifically speaks to being good for turbochargers.) I'm still on the fence as to whether I want to switch from 5w30 to 0w40 on our Z06 Corvettes, but I definitely do not want to run EP in our LS6 and LS7 motors if it has inferior wear protection!.