Originally Posted by Quoydogs
You for got Castrol and Redline sucks! Your #2 is dead wrong. If you have worn bearing or bad valve guides just move up to a 20-50 or straight 30w. You can then still use syn. and have way better protection without the burn off.
I agree. Castrol is quality, no question.
As far as moving up in weight to 20-50 for cars which may have worn out valve guides, journals and bearings, it may be ok, in fact I think it'll be just fine. What you don't want to do is use a heavier synthetic oil on car with present leaks.
Redline, is not an oil I would personally use, and the Pennzoil Platinum has come with a lot of hype into the market, I've used it on my Z06 Corvette and I wasn't too impressed with it.
I went back to Mobil-1. (GM recommended)
Royal Purple is another favorite of mine. The whole line of products for your tranny, differential and stuff like that works real well.
Amsoil, I'm yet to try it, but heard a lot of good things about it.
Shaeffer Synthetic Oil is also an excellent oil with superior protection properties.