2020 MERCEDES-BENZ S600

Typical onset: 40,000-80,000 mi

Symptoms: Metallic knocking or ticking from lower engine that worsens under load, Oil pressure warning light or low oil pressure readings on startup, Metal shavings or glitter in oil during changes, Sudden catastrophic failure with loss of power and severe knocking

Fix: This is the big one. Oil system design allows momentary starvation during hard acceleration or low oil levels. Once bearings score, it's engine-out for short block replacement or full rebuild. Expect 60-80 labor hours for short block swap, 80-100+ for full teardown and rebuild. Many shops won't touch V12 work—you're looking at dealer or specialty euro shops only.

Estimated cost: $35,000-65,000

Typical onset: 50,000-90,000 mi

Symptoms: Oil residue visible on top of engine around turbo area, Burning oil smell from engine bay, Blue smoke on cold start or under boost, Slow oil consumption between changes

Fix: The braided oil feed lines to both turbos develop leaks at crimp fittings. Not a difficult job mechanically but access is nightmarish—requires removing intake plenum and various heat shields. 8-12 hours labor. Critical to address before oil starvation causes the bearing failure mentioned above.

Estimated cost: $2,800-4,200

Typical onset: 60,000-100,000 mi

Symptoms: Transmission slipping or harsh shifts, Milky or pink coolant in expansion tank (coolant-trans fluid mixing), Transmission overheating warnings, Coolant loss with no visible external leaks

Fix: The internal trans cooler in the radiator fails, allowing coolant and ATF to mix—death sentence for the 7-speed MCT transmission if not caught immediately. Requires radiator replacement, full transmission fluid flush (multiple cycles), and often new transmission if contamination went unnoticed. Radiator alone is 6-8 hours; if trans is cooked, add another $15k-25k. Preventive radiator replacement at 60k is cheap insurance.

Estimated cost: $2,500-4,000 (cooler only), $18,000-28,000 (if trans damaged)

Typical onset: 50,000-80,000 mi

Symptoms: Clunk when shifting from Park to Drive or Reverse, Vibration felt through center console at idle, Excessive driveline movement visible during throttle application, Thud when lifting off throttle

Fix: The hydraulic transmission mount deteriorates and loses its damping ability. Straightforward replacement but requires supporting the transmission. 3-4 hours labor. Not urgent but uncomfortable and worsens shift quality perception.

Estimated cost: $800-1,400

Typical onset: 60,000-100,000 mi

Symptoms: Rough idle especially when cold, Misfires under light throttle (check engine light with P0300-series codes), Loss of power and throttle response, Fuel economy decline of 2-3 MPG

Fix: Direct injection means no fuel washing over intake valves—carbon builds up and chokes airflow. Requires walnut blasting all 12 intake ports with engine disassembly. On a V12, this is 16-20 hours labor because of the valley access. Some shops recommend doing spark plugs and ignition coils simultaneously since you're in there. Consider preventive cleaning every 60k miles.

Estimated cost: $3,500-5,500

Typical onset: 70,000-120,000 mi

Symptoms: Vehicle sits low after sitting overnight (usually one corner first), Suspension warning light with 'visit workshop' message, Compressor runs excessively (audible under car), Uneven ride height side-to-side

Fix: Airmatic struts develop leaks at the rubber bladder. While not S600-specific, the rear struts are common failure points. Each strut is 2-3 hours labor. Often the compressor is worn out from overwork by the time you notice the leak. Budget for all four corners plus compressor if mileage is over 100k—doing one at a time is penny-wise, pound-foolish.

Estimated cost: $1,800-2,800 per strut, $2,200-3,200 for compressor