BMW designed the S65 and S85 with approximately half the industry standard oil clearance. This is a trendy move among some auto manufacturers to increase gas mileage and increase horsepower. But when they do it, like in the Toyota Prius, the auto manufacturer also specifies a very thin oil to match the very small oil clearance. BMW dropped the ball here and is using very small oil clearance and very thick 10W60 oil. Many consider this its own recipe for disaster. But here's what is believed to be happening in the S65 and S85 engines.