The F90 M5 with its S63B44T4 engine is a beast when healthy, but the twin-turbo V8 has a documented weakness with rod bearing wear and the ZF 8HP76 transmission can develop cooler and mount issues under hard use. High-performance maintenance is not optional.
Rod Bearing Wear / Crankshaft Damage
Occasional · high severityTypical onset: 40,000-80,000 mi
Symptoms: Metallic knocking or ticking on cold start that disappears when warm, Metal shavings or glitter in oil during changes, Low oil pressure warning at idle after warmup, Catastrophic engine failure if ignored
Fix: Preventive bearing replacement is 18-22 hours labor; catastrophic failure means full engine rebuild or replacement at 60-80 hours. BMW updated bearing specs but early S63TU engines still at risk. Many owners do preventive service at 50k-60k mi.
Estimated cost: $6,000-12,000 preventive; $25,000-45,000 for full rebuild/replacement
Transmission Oil Cooler Leaks
Common · medium severityTypical onset: 50,000-90,000 mi
Symptoms: Transmission fluid puddles under vehicle, usually passenger side, Low transmission fluid warning on iDrive, Burnt transmission fluid smell, Harsh shifting or delayed engagement if fluid level drops significantly
Fix: External cooler lines crack at crimp points or cooler itself develops leaks. Replacement is 4-6 hours including fluid refill and relearn procedures. Common enough that many shops stock the parts.
Estimated cost: $1,200-2,200
Transmission Mount Failure
Common · medium severityTypical onset: 60,000-100,000 mi
Symptoms: Clunk or thud on hard acceleration or deceleration, Vibration through drivetrain during shifts, Excessive driveline movement visible when rocking car in gear, Harsher shift quality especially in Sport+ modes
Fix: The rear transmission mount takes enormous abuse from launch control and aggressive driving. Replacement is 2-3 hours. Upgraded polyurethane mounts available for track-driven cars but increase NVH.
Estimated cost: $600-1,200
Fuel Filter Clogging / Fuel System Contamination
Occasional · medium severitySymptoms: Intermittent misfires under load, especially at high RPM, Loss of power or hesitation during hard acceleration, Rough idle or stumbling after fillup, Check engine light for fuel trim or misfire codes
Fix: In-tank fuel filter assembly gets contaminated from poor fuel quality or debris in tank. Requires dropping fuel tank, 4-6 hours labor. Some cars affected by recall for tank venting but filter still maintenance item.
Estimated cost: $800-1,500
Turbocharger Wastegate Rattle
Occasional · low severityTypical onset: 30,000-70,000 mi
Symptoms: Rattling noise from engine bay on cold start or deceleration, Metallic chatter between 1,500-2,500 RPM under light load, No performance loss initially but can progress to boost control issues
Fix: Wastegate actuator arms develop play. Early cars got revised actuators under warranty. Replacement per turbo is 8-12 hours (engine access intensive). Many owners live with the noise if no boost issues present.
Estimated cost: $3,500-6,000 per turbo
Rear Differential Cooling System
Rare · medium severityTypical onset: 70,000-120,000 mi
Symptoms: Whining or howling from rear differential under load, Burnt gear oil smell after spirited driving, Clunking during direction changes if severe, Overtemp warnings on track use
Fix: Active M differential gets hot, especially with AWD system sending power rearward. Cooler lines can leak, fluid degrades. Diff fluid service every 30k mi critical. Full diff rebuild is 10-14 hours if damaged.
Estimated cost: $400-800 for service; $4,000-7,000 for rebuild
Buy one if you budget $3,000-5,000/year for maintenance beyond basics and have $15,000 set aside for the inevitable engine or transmission work — these are 600+ hp maintenance queens, not Camrys.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.