Just want to throw this out, I know this has nearly been beaten to death, but I think it warrants further discourse. Group III vs. Group IV. I know this board is a pro- Grp. Iv place, evidenced by the poll. But, I think that this once rational position is being swept up into an emotional movement. As I understand Grp. III is the product of catalytic reaction and not just severe hydrocracking. So you should be getting a distinctly different 'new' molecule and not a 'saturated' one as with Grp. II, I have no idea what differentiates a Grp. II+. As for Group IV, that's old technology, almost 30 years old now, good 'ole Mobil SHC. I'm no chemist but this is what I've put together from what I've read. Ultimatly a limit on the price of a product is in place to assure market share, the rest is quality and marketing. Some people are very upset with Castrol and the whole synthetic debate. But, it may be that with a Grp. III based oil a superior add. pack can be afforded. Now Castrol certainly doesn't skimp on the marketing but doesn't making the best oil possible at the price point make sense? Especially when more and more engines require sythetics. It's a matter of approach I think, the one major still using exclusivly Group IV is alone, all the other players in that market are using Group III. Maybe they've seen the light, maybe you can get better oil using Group III with a more sophisticated add pack than you could afford with Group IV oil. Or maybe it's just a better spread. Who knows, maybe one of you? I just don't understand the almost viscious bias against Group III basestock oils? Certainly there are some good Group III oils? All the majors make them, does anyone use them?