2016 MERCEDES-BENZ S65 AMG

Typical onset: 40,000-80,000 mi

Symptoms: Metallic knocking from engine bay, especially on cold start, Loss of oil pressure warning, Metal shavings in oil during change, Sudden engine seizure in worst cases

Fix: Engine-out teardown required. Most shops replace short block or do complete rebuild with upgraded bearings. 60-80 labor hours for R&R plus machine work. Many owners find out during routine oil analysis or catastrophically.

Estimated cost: $35,000-55,000

Typical onset: 50,000-90,000 mi

Symptoms: Excessive oil consumption (1 qt per 1,000 miles or worse), Blue smoke from exhaust on startup or acceleration, Misfires and rough idle, Loss of compression on cylinder leak-down test

Fix: Requires complete engine disassembly, piston replacement, cylinder honing/boring if needed. 70-90 hours labor. Common on engines with aggressive tune or heat cycling. Often discovered alongside bearing issues.

Estimated cost: $28,000-45,000

Typical onset: 60,000-100,000 mi

Symptoms: Transmission fluid puddles under vehicle, Burnt transmission fluid smell, Harsh or delayed shifts when fluid gets low, Low transmission fluid warning on dash

Fix: Replace cooler lines and sometimes the cooler itself. 4-6 hours labor including trans fluid flush. Lines corrode where they pass near exhaust components. Catch it early before damage to 7-speed MCT.

Estimated cost: $1,200-2,200

Typical onset: 70,000-120,000 mi

Symptoms: Rattling noise on cold start that disappears when warm, Loss of boost pressure and sluggish acceleration, Check engine light with underboost codes (P0299, P0234), Overbost or erratic boost delivery

Fix: Wastegate actuator rods wear and seize on these twin-scroll turbos. Typically requires turbo removal and rebuild or replacement. 12-16 hours per side, often do both. Engine-out not required but cramped V12 bay makes access brutal.

Estimated cost: $4,500-8,000

Typical onset: 50,000-80,000 mi

Symptoms: Clunking when shifting from Park to Drive/Reverse, Vibration at idle in gear, Excessive drivetrain movement visible when rocking car, Harsher shift feel

Fix: Hydraulic transmission mount fails from V12 torque and weight. Replace mount, sometimes involves dropping exhaust for access. 2-3 hours labor. Straightforward job but surprisingly expensive OEM part.

Estimated cost: $800-1,400

Typical onset: 60,000-100,000 mi

Symptoms: Hard starting or extended cranking, Loss of power under load, especially above 4,000 RPM, Rough idle and hesitation, Fuel pressure fault codes

Fix: V12 direct injection system has two high-pressure pumps. Filters clog from fuel contamination, pumps fail from running dry. Filter changes are 1-2 hours, pump replacement 6-8 hours each. Mercedes recommends filter service every 20k but many skip it.

Estimated cost: $400-800 (filters), $2,800-4,500 (pump)

Typical onset: 80,000-130,000 mi

Symptoms: External oil leaks at head/block interface, Coolant loss with no visible external leak, White smoke from exhaust, Overheating or erratic temperature readings

Fix: V12 layout means double the work—both banks typically done simultaneously. Engine doesn't always need removal but highly recommended. 50-70 hours labor. Head machining often needed. Usually a "while you're in there" becomes full refresh.

Estimated cost: $18,000-28,000