Ask any E60 M5 owner about the most important maintenance topic and the answer is usually the same: connecting-rod bearings.
What are rod bearings?
Each connecting rod links a piston to the crankshaft. Between the rod and the crankshaft sits a thin bearing shell, separated from the crank by a film of oil. As long as the oil film is healthy, the parts never actually touch.
Why the S85 is sensitive
The S85 revs very high and was built with tight internal clearances. Over time and mileage, bearing wear can increase. If wear goes too far, the oil film can break down, leading to severe engine damage. This is why many owners treat bearing replacement as preventative maintenance rather than waiting for symptoms.
Warning signs
- Metallic particles in the oil or oil filter.
- Knocking noises, especially under load.
- Oil analysis results showing elevated bearing metals.
By the time a noise appears, damage may already be significant — so prevention is preferable.
Prevention
- Warm the engine fully before using high rpm.
- Change the oil frequently with the specified grade — see our oil guide.
- Consider periodic oil analysis to track wear trends.
- Discuss a preventative bearing replacement with a specialist, especially on higher-mileage cars or cars without documented work.
The replacement job
On the S85, bearings can typically be replaced with the engine in the car, though it is a substantial job. Use a specialist experienced with BMW M engines and ask which bearings and bolts will be used.
Educational content written by enthusiasts. Always follow official service information and a qualified technician.