Originally Posted By: Bottom_Feeder
Who cares if the price is good if it's really not ideal for your application? $2/qt is not that great considering you can get something like NAPA syn in 5w30 for only a little more every day of the year.
If the LS1 is run hard the 0w-40 or 0w-30 A3/B4 make actually perform better than the 5w-30's, especially for a year long OCI of 8K-12K miles. The 0w-40 will shear down into a 30 grade after a "few" thousand miles, the 5w-30 will shear down into a weak 30 grade. The Pennz/M1 40 grades have a stouter add pack than the 5w-30. Some of these 40 grades only start with a 100c vis in the 12.8-13.2 range....much weaker than the 13.8-14.2+ seen on the stronger 40 grades.
You can decide among the 3 choices for your add packs as those vary quite a bit - high sodium - lower calcium (NAPA or Valvoline 5w-30). High calcium - no magnesium or sodium (Pennzoil, QSUD, M1 0w-40, Valvoline 0w-40 or 5w-40 HST). Or high magnesium - lowered calcium (M1 5w-30, Castrol Edge 0w-40).
While Napa may be $2.99 on sale, the Pennzoils you are considering are $2.00 this week. And after rebate, only 0-15c per quart. Tough to beat. NAPA doesn't carry the A3/B4 certs either. If you want those in a similar product you have to go up to the Valvoline 0w-40 or the HST which are also high calcium - no sodium oils like the M1 and PP. I've seen a few hundred threads on what to put into my LS1. I can't recall anyone using 5w-30 NAPA synthetic. The M1, PP, PU, Castrol Edge, Amsoil, Royal Purple, QSUD, are the ones I've seen the most often. Valvoline Synpower 30/40 grades are in their somewhere too, though far less frequently than most of those others.
None of us knows what's "ideal" for the OP's application as none of us know their driving style, OCI's, or even their climate. It's their decision
