This link shows some of the politics/EPA involved with emissions and motor oil.
In America you can build a great car but are forced to use whatever oil is being made by big oil, and must push big oil to improve the quality.......it's a slow process......the oil quality always lags engine technology.
Earlier I showed the opposite is true in Europe allowing for much higher quality oil........hence the existence of the much-coveted German Castrol at Auto-Zone.
http://www.ilma.org/advocacy/l...dmarketers060204.pdf