Originally Posted by ChocoTaco369

i say go mobil 1 5W-40. the problem with mobil 1 5W-30 is it protects poorly once it's warmed up. the 30 weight rating may as well be a high 20 weight. it's too thin and that's why mobil 1 30W's generally show high wear numbers on the LS1.

with the 5W-40, you'll get the same cold start protection and your engine should sound the same upon startup. it'll just protect better once it runs operating temperature. the mobil 1 5W-40 runs close to the same thickness as GC 0W-30 at operating temperatures. though the oil base isn't as exotic, it's surely better than mobil 1 5W-30.

mobil 1 10W-30 will keep your engine noise the same once the oil heats up as 5W-30 and 10W-30 would be the same thickness and protect the same once operating temperatures are achieved, so skip right over mobil 1 10W-30.

Originally Posted by TORCHD 02 TA

anthony i do not want the same protection as GC.. you see that is what my motor sound so wierd.. i honestly might do the 10w30 and 15w50

like you said in the pm.. my ls1 might like the thin oil??

Originally Posted by ChocoTaco369

mobil 1 5W-40 is even thicker than your mobil 1 5W-30, so it'll further supress noise. you gotta understand that even while GC 0W-30 for some reason was louder for you, it was likely protecting better than mobil 1 5W-30. M1 5W-30 often produces high wear numbers. GC 0W-30 is known to be loud at startup but after it warms up it SHOULD fade. i would say go 5W-40, it'll work even better for you. i was joking about your LS1 liking a thinner oil, that's unusual as hell. maybe you got a bad batch of GC? who knows.