Jean, I will probably do that. I'll wait to see my wife's initial RP results first though, before I decide to commit to buying a full case again (over $100 worth of oil!)
Rob, I think the LT1 engine would do well on a high 30 to low 40wt oil, but unfortunately the Pennzoil 15w40 is a thicker 40wt at 15.5 cst, so I think it might be too thick to offer the best protection for your engine. If you're gonna go 40wt, look for something on the lower end, 12.5 to 14.0 cst if possible.