Quote: So what do you guys think is so special about your oils? I never know what to buy because everyone claims their's is best anyway. I've been using Pennzoil 10w30 or Castrol GTX 10w30. I used to run 15w40 Rotella. And I've used 10w40 Royal Purple, still have half a case in the shop. I can get Mobil 1 10w30 easy enough and thought I'd try that. Never had a problem with any of them. Pennzoil 10w30 is in my car now though.
Don.
People prefer “special” oils because of what’s formulated into them.
Nothing wrong with Pennzoil 10w30, Castrol GTX 10w30 or Mobil 1 10w30, but they are API (SM) rated oils. SM rated oils are required to have lower zinc and phosphorus levels which is not a problem in newer cars.
If you’re running a older modified V8 with a high performance flat-tappet camshaft, you need motor oil with higher levels of zinc and phosphorus.
Do a search here of the board for zinc and phosphorus (ZDDP).
