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.
Engines with clearance too small, couple with oil too thick, leads to premature rod-bearing related engine failures. With clearance too small and oil too thick, the lubrication around the bearing is marginal. Some metal-to-metal contact is made between the bearings and rod journal. The oil and rod bearings overheat. Some bearings seize on the crankshaft, while others will "spin" and cause a crankshaft failure.
This is a serious concern for M3 owners, especially those that have higher mileage or are supercharged/tracked often. Engines with clearance too small, couple with oil too thick, leads to premature rod-bearing related engine failures. With clearance too small and oil too thick, the lubrication around the bearing is marginal. Some metal-to-metal contact is made between the bearings and rod journal. The oil and rod bearings overheat. Some bearings seize on the crankshaft, while others will "spin" and cause a crankshaft failure.
It's rare to see bearings without at least some sort of premature surface wear, it's good to jump on this issue soon. For those looking to keep their vehicles for extended use, our Rod Bearing Service is a must. Don't let your BMW engine become a casualty.
