It comes down to performance, price and marketing. Primus makes a lot of good points. Mobil 1 is tough to beat though. They make the additives/PAOs, test many oils in racing and are always developing new technology. Others do this also, but EM takes pride in Mobil 1 as their flagship product. They are the only mass market PAO based oil. This gives them the edge of the grp III players who take shortcuts and don't sell true synthetics to the retail market. Mobil 1 has proven to be among the best oils out their, even beating RL in many cases. When you consider what you get for $4-$5qt, it's an incredible bargain.
[ May 05, 2004, 05:23 PM: Message edited by: buster ]