what oil is best for these tahoes?

[Spar]

Are you saying you run straight 30 wt motor oil? No, that's bad. GM recommends using 5w30 oil in these motors. If you are using straight 30 wt oil you are causing excessive engine damage at start-up.

I went looking for the answer to my question, and found *most* of it LOL I understand my '99 Tahoe is designed to use 5-30w, and that's what I'm using. However, does age/mileage change the requirement at all ? Is the 5-30w requirement when it rolls off the line, still valid 182K miles later ?

 

[squeasel]

Weight should correspond with the operating conditions and most should find that 5-30 is good. One item that has changed since this thread started is oil API. I have read that the current standards of SM and SN contain less of a zinc-phosphate additive than the prior standard of SL. The zinc-phosphate additive (ZDDP, I think) is needed for better push-rod lubrication. So if you went the Mobil 1 route, you will find the "High Mileage" blend is API SL while most of the other blends are SM/SN. My 2 cents.