I have been using 10W-30 Castrol GTX in my 94 suburban from day one. I don't believe that it is even spec'd for that oil weight. Regardless, it has 174k on it and runs amazing. I now have a used 01 suburban with a 5.3L and was thinking of using the same oil. What weight are you guys using? Is it more crucial to use spec'd oil weights with the newer gen engines, or is it really not a big deal?

 

man has this topic been talked to death.

the best advice ever: Read the manual.

I'm not being smart. These people took a lot of time and money to build you an engine... they know what it needs.


https://chevroletforum.com/forum/sho...ghlight=weight

 

sorry to get your panties in a bunch and thanks for the link, very helpful. Didn't realize what a sore subject it was.

 

Which as we discussed, is strictly a comfort thing!

 

The thicker oil will cut down on your gas mileage a tad, but not enough to notice. other then that, its not going to hurt you or do you any good either. Personally, I would just stick with the 5w30. There is no need to run heavier weights on the newer trucks