motorman

i have been using amsoil syn. in my posi equipted silverado for over 100,000 miles and the posi works fine. the additive is use to prevent the gauling of the posi plates.it makes the lube more slippery. with regular rear gear lube GM says to change the lube every 7500 miles or you will have a "grabbing efect" in the turns but with syn that does not have to be done.

Fred99LS1

When I bought my 99 Z28 a lil while back I changed the oil & put Quaker State 10W-30 Full Synthetic oil in it. I would have put Mobil 1 10W-30 full synthetic in but Autozone was out. I have noticed that my oil pressure runs extremely high. My oil pressure runs at 45 psi when idling at 210 degrees & soars past 70 psi when at WOT. It kind of scares me to see it go so high. Would I be better off running 5W-15 full synthetic?

I'm sure that synthetic oil allows for more power. Back in the day I had my 85 & 88 Mustangs I read a article in Mustangs & Fast Fords that had a dyno comparison with 10W-30 multi grade oil & 10W30 full synthetic oil. The synthetic oil was good for 7 RWHP on a Mustang.

WS6FirebirdTA00

iTrader: (33)

just make sure the crank case can breath and that oil pressure should be fine. the rec runnig 5/30 so 10/30 is the same just colder temps u will see more pressure. when i idle mine is about 40-45 also i wouldnt worry its nomal pressure i think

sawedoff

iTrader: (3)

Yes, I would go to the synthetic in 5w-15. I have been using Neo Synthetic racing oil in 0w-5 in my 99' Camaro since it was new.