Even BMW's Greatest Engine Can't Outrun Neglect

Yahoo

4 days ago

Even BMW's Greatest Engine Can't Outrun Neglect originally appeared on Autoblog.
The BMW S85B50 5.0-liter V10, found in the E60 M5 and E63 M6, remains one of the boldest engines ever fitted to a production sedan. A naturally aspirated marvel, void of any connection to other production power plants, it revs up to 8,250 rpm and produces over 500 horsepower in stock form. It was the German marque's love letter to its BMW Sauber Formula One endeavors. The sound alone, an orchestral scream of ten cylinders, cemented its status as one of the best engines ever made by BMW.
But with that performance and aural renown came at a price. The S85 is notoriously high-maintenance. Regular oil changes, rod bearing inspections, premium fluids, and an owner who knows what they're doing are all non-negotiable. These engines were never meant for casual ownership or neglect.
And yet, as a recent teardown video reveals – courtesy of our favorite engine coroner, I Do Cars – not even BMW's best engineering can overcome years of corner-cutting maintenance.
The engine under the spotlight came from a 2006 M6 with 121,000 miles on the clock, a surprising mileage for an S85 given its condition. Bought at auction, the car wasn't running, and the engine was locked up.
The story inside was quickly revealed at the beginning of the teardown: oil varnish coated the internals, indicating long oil change intervals with cheap fluids. The valve covers and cylinder heads showed signs of excessive sludge buildup, and the oil control rings were so plugged that the engine was visibly burning oil.
Surprisingly, the intake ports and some top-end components were relatively clean, suggesting this M6 wasn't driven hard, but rather babied like a regular 6er. That may have saved it from a more dramatic failure, but treated like a regular commuter, it died a slow death.
View the 3 images of this gallery on the original article
The fatal failure came in the form of a rolled rod bearing. Two bearing shells had fused and stacked inside the rod, pushing the piston slightly higher in the bore. That minor increase in travel was enough for the piston to strike the cylinder head. The damage wasn't dramatic – no holes in the block, no thrown rods – but it was enough to kill the engine.
For all its brilliance, the S85 is not bulletproof. It demands devotion from an enthusiast who knows the ins and outs of owning a beautifully engineered, performance mill. And, evidently, when it doesn't get it, the results are as inevitable as they are heartbreaking.
Even BMW's Greatest Engine Can't Outrun Neglect first appeared on Autoblog on Jul 6, 2025
This story was originally reported by Autoblog on Jul 6, 2025, where it first appeared.