Ok, so here is a question for all of you. I have a 91 Z 305 TPI with about 115,000 on it. At the moment I'm running Mobil 5w-30 in it. What would you all recomend I run, and why? AND what do you run, in which engine, and why?

Brian

 

I have a 305, 198,750 on the odometer as of today.. have run valvoline 10-40 in it ever since i got it back in '99. I run the 10-40 because it tends to keep preassure better during the sumemr when it is driven in the stop and go rush hour traffic. especuially on those 85+ degree days when you can cook eggs in the middle of rush hour traffic on the asphalt. Never had a problem with the engine though.. 5w30 on a really hot day doing the stop and go move 7 miles in 1 hour thing and i would be on the side of the road letting the engine cool off cause my oil pressure would be non exsistant on the guage.

 

Oh yea.. I do however run 10w30 synthetic in my 84 Z HO. (305 / t5 tranny) Holds pressure nicely and the oil stays nice and clean.. also stands up well in the early spring and late fall when temps get down there before the snow flys. Prety much a good all around oil is the 10w30. I believe that is what the manuals say is a good year round oil.

 

Heh, I wish it was 85 here. Try 105 heat index here in Florida. I use 10w 30. My T/A never sees under 30PSI at idle and never sees temps over 220 (max)

 

like my second post said. 10w30 is a good all around oil. I mostly use 10w40 because of the age of my engine.. it is a pre 80' engine. no work done to it other than timing chain. so the heads are in poor condition and lighter weight than 10w40 on hot days in stop and go it leaks past rings and valve seals causing a little smoke.. which is annoying.. I just run 10w40 tis a good oil for the summer. and is spec with what is recommended for how the car is driven