Yep, I run the M1 0W40 in both the Camaro and my Silverado too. Seems to work great and has been fine in the cold weather. If I didn't have so much 0W40 kicking around I would probrably just stick with the M1 5W30.

The German Castrol seems to be the best now, but like everybody says, it's too hard to come by.

 

Gm has spent millions of dollars in research and development. if they require 5w 30, i would run it. Gm also uses 5w 30 Mobil 1,i n the corvette since 1985up. I would run what is required, or the synthetic. Unless you have a built motor and require other wise.

Just my opinion,
J

 

I've used M1 5w-30 for many years...current truck,86 Chevy van (305,auto) and a 93 Civic(engine and transaxle). I check oil often--3 or 4 times a week--it has always looked good on the stick...not thinned-out. The van had 125K when I sold it...Civic has 206K...both maintained good power.
I live in Texas,too,and made a point to check how it looked when it was hot weather...no problems. I use a little Lucas oil stabilizer in the Honda.

 

im in texas and have used m1 10w30 on all of my trucks. never gets too cold here.

 

i use 10w30 in the winter and 10w40 in the summer