I was just wondering is ther a real benefit of running a hight milage syn. I was thinking maybe the new M1 5w30 or 10w30 but they dont have the energy star burst would I loose any power/fuel milage with it vs a dino 5w30 or syn 5w30
I don't dispute that there are engines that can benefit from the HM oils, M1 and otherwise. That said, I ran my late great 88 Civic almost its whole life, ten years and over 150k miles, on the then-standard M1 5w-30 (I tried 10w-30 once or twice), and never had any problem at all.
how are they about controlling leaks do the actually restore seals? or is that just a sales pitch
No one is even sure that the oil has more seal conditioners. Folks have asked Mobil point blank, and received only the standard corporate bee ess.
OTOH, there are several testimonials floating around here suggesting that M1 (and other MH oils) actually can reduce seal leakage.
My own experience, with a leaky distributor seal, has been mixed. Since switching to M1HM 10W30, the seepage has slowed somewhat, but is far from cured. YMMV!
It can't hurt to try it, there's no way it will hurt the car.
In addition to the Zinc and Moly, both flavors of M1HM have a big swig of Boron, presumably integrated into an anti-wear additive.