6.0 with a 93 tune? Mpg?

[Cowpie]

My contention is that many folks let their paranoia gland run amok and worry about such things as the dexos1 compliance or you will void the warranty. That is not true. GM TSB 13-00-90-001, while extolling the virtues of dexos1 and how it will prevent the collapse of mankind, also admits that if you cannot get a dexos1 oil, a ILSAC GF-5 oil will work and not void warranty. Most major brands meet that spec, especially the boutique oils like Amsoil, Redline, Royal Purple, etc. So one does not have to toe the line and only use an oil off the "approved" dexos1 list.

 

And the GF-5 spec is tougher regarding ethanol in fuel. Really has me wondering why GM would promote ethanol use, and then argue for a oil spec that is weaker regarding ethanol use. See for yourself.... http://www.gf-5.com

 

Either way, no dealer is going to check or be able to tell if your oil doesn't meet the needs of your motor. And unless there is a reason to do so, I am not sure a dealer is going to waste time on checking for tune changes either. That is, unless you broadcast to the planet that you are using a tune.