BMW S85

BMW M's 5.0 V10 — the E60 M5's engine, and the E63 M6's. BMW's only production V10.

It was designed from a Formula One brief and it behaves like it: 8,250 rpm, individual throttle bodies, and an engine that makes very little of its power below five thousand. An owner reporting that it feels slow in traffic is describing the design.

⚑ The rod bearings are the failure this engine is known for, and the consequence is total. The clearances were tight from new, the service interval was long, and the bearings wear silently until they do not — by which point the engine is scrap. Preventive replacement at a sensible interval is the accepted practice, not an over-reaction, and oil analysis for bearing metal is how the question gets asked cheaply.

Its throttle actuators are the second known item, and they set a code and put the engine into a reduced-power mode rather than failing quietly. They are rebuildable.

Oil grade and level are not routine here. A dry-sumped, high-revving engine with marginal bearing clearances is unforgiving of both, and most of what goes catastrophically wrong with an S85 traces back to one of them.

The SMG gearbox behind it in most cars is a separate diagnosis and the source of many complaints attributed to the engine.