I found a cheap S85 with 100,000 miles — is it worth buying?

At 100,000 miles an S85 engine replacement should be treated as a full build project, not a drop-in swap. Budget for rod bearings, VANOS units, throttle actuators, and all ten coil packs as a minimum. If the price reflects those costs it can still make sense. If the seller is pricing it as a running replacement — walk away.

Can I use an S63 from an X5 M in my F12 M6?

The S63B44T2 variant used in the F13 M6 is shared across the F10 M5, F85 X5 M, and F86 X6 M. Fitment is generally compatible but software, harness routing, and accessory placement differ between chassis. Confirm your production date and DME part number with our team before ordering — we verify S63 cross-chassis fitment as part of our VIN matching process.

What does Grade A mean on your M6 engines?

Grade A means the unit was sourced from a running donor vehicle, passed compression testing and visual examination, shows no signs of cracks, leaks, or external damage, and has verified documented mileage. It is the highest grade we assign — and all eight currently listed M6 units carry it

Used BMW M6 Engines for Sale – S85 V10 & S63 Twin-Turbo

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Three types of buyers search for used BMW M6 engines for sale and each one is looking for something completely different. Some want the S85 V10 because nothing else sounds or revs like it. Some want the S63 twin-turbo because real-world speed and daily reliability matter more than a screaming soundtrack. And some want cross-model compatibility the S63 fits the M5, X5 M, and X6 M as well, making it one of the most versatile BMW performance engines in the used market. All three groups will find what they need in our inventory above.

The S85 — BMW V10 Production Engine

The BMW M6 V10 is the S85 a 5.0L naturally aspirated V10 built directly from BMW's Formula 1 experience. It produces 507 horsepower at 7,750 RPM, revs to 8,250 RPM, and uses ten individual throttle bodies one per cylinder. It won the International Engine of the Year award three consecutive years from 2006 to 2008. No turbos. No forced induction. Pure mechanical response from idle to redline.

Finding a clean S85 engine for sale has become genuinely harder every year. These units are no longer in production and the supply of low-mileage donor vehicles shrinks annually. The 2006 unit we have listed at 45,241 miles is among the lowest-mileage S85 units available in the US market right now. Every S85 engine for sale at Moon Auto Parts goes through compression testing across all ten cylinders and a full visual examination before it is listed. Rod bearing condition the most discussed S85 maintenance point is flagged in our inspection report on every unit.

The S63 — The Engine That Changed the M6's Character

The F12 and F13 generation M6 switched to the S63 a 4.4L twin-turbocharged V8 producing 560 horsepower and 500 lb-ft of torque in standard form, and 600 horsepower in Competition Package specification. Where the S85 demands high RPM to deliver its power, the S63 pulls hard from 1,500 RPM and holds it across the entire powerband.

The S63 engine for sale also crosses over to the F10 M5, F85 X5 M, and F86 X6 M meaning parts support and mechanical familiarity are significantly wider than the S85. For buyers who drive their M6 daily and want the most capable BMW M6 engine replacement option with strong long-term parts availability, the S63 is the practical choice. Our F12-generation units range from 26,047 to 72,190 miles all Grade A, all VIN-matched before shipment.

Browse all BMW M6 engine options by year and specification at the Moon Auto Parts BMW engine listings.