I have been using M1 10W30 for a long while, it seems. This add brew is enticing; one benefit is to increase viscosity of this oil specifically. I drive in SoCal sometimes when its over 100 F, and M1 will definitely burn a little under those conditions. The question I have is whether the cold vis. is also increased, and if so how much? Has anyone used it in an engine that has cold piston slap, and did it make any difference? A lot of folks in the SHO community don't use M1 because of this problem.
Mike
Mike