92 Yukon 5.7 (New engine w/ 20000 miles): Engine Oil??

[TerryKing]

Hi Everyone,

I have free access to some Shell Rotella T4 oil 5w-40 which is high quality recommended for diesels.

Any reason I shouldn't use this in my regular GM350?

Thanks!

 

[bigfootchiro]

Is it T6 full synthetic 5w-40 or T4 15w-40? Idk that I’ve seen a T4 5w-40

 

[TerryKing]

Hi, it's T4 15w-40. I can get 20+ quarts of this for free... Supposed to be very high quality. The older GM's didn't spec. full synthetic, although I use it in my 2012 Tahow 5.7..Thanks!

 

[bigfootchiro]

Well, it does have an SM api rating, which any S rating would be ok for gas engines, but it’s the only S rating for that oil. Honestly, if it were me, I wouldn’t. $50 here and there for an oil change offsets the cost of potential harm that oil may do, in my book. T4 is great oil. Used to use it in my Cummins, but not for gas engines. If you were talking about T6 5w-30 or 10w-30, I’d say go for it and send some my way haha.

 

[zraffz]

Regardless of being a diesel or gas oil, any 15w40 oil does not belong in a freshly built sbc.

I always rebuild my motors on the tighter side if tolerances and generally run 5W30.

 

[RED TAHOE LS]

Well, it does have an SM api rating, which any S rating would be ok for gas engines, but it’s the only S rating for that oil. Honestly, if it were me, I wouldn’t. $50 here and there for an oil change offsets the cost of potential harm that oil may do, in my book. T4 is great oil. Used to use it in my Cummins, but not for gas engines. If you were talking about T6 5w-30 or 10w-30, I’d say go for it and send some my way haha.

Times two......good luck.
David g.....

 

[TerryKing]

Thanks, Guys.. I appreciate the info and opinions.. I'll stay with good synthetic.

 

[swathdiver]

It's not so much all those ratings and standards to watch for but the viscosity of the oil as Josh said. Use the viscosity it was designed for unless you've redesigned it. I think those were 5W30 or 10W30 back then. The diesel oil would be too thick.