I have used M1 in the Vette for its 6 1/2 yr life...and, many P Cars come
with M1 in it/& rec'd.

I've used it in the X, too...along with Castrol, and other synths.

I am of the mind that for daily driving, almost any name brand synth is
very good stuff and light years ahead of the oils I used back in the '60s
and '70s, and even '80s. Very interesting arm wrestle initiated by Valvoline.

I too, am not trying to initiate another oil thread, ...