I just saw a very short PBS program about Castrol developing race oils for BMW/Williams Formula 1 race cars. The Castrol spokesman said Castrol was developing oils for specific BMW engines together with the engine designers to get the perfect match. Ralph Schumacher said a few things, most notably that the Williams cars gained 5-8hp by using "thin" oil. He didn't say how thin. He added thin oil will also lead to a performance increase in street cars, but at the cost of bearing wear, which he said (grinning), wasn't an issue with race cars that didn't that have to go 100k miles and more. Just thought I'd share.