2010 MERCEDES-BENZ S600

Typical onset: 60,000-120,000 mi

Symptoms: Metallic knocking or rumbling at idle, especially when hot, Low oil pressure warning (often your only advance notice), Metal shavings in oil during changes, Sudden catastrophic failure with no warning in worst cases

Fix: Engine-out full teardown. Replace all main bearings, rod bearings, inspect crank for scoring (often needs machining or replacement). If crank is damaged, you're into full rebuild territory with pistons, rings, gaskets. 40-60 hours labor minimum for bearing replacement alone; 80-120 hours for full short-block swap or rebuild.

Estimated cost: $15,000-35,000

Typical onset: 80,000-140,000 mi

Symptoms: Loss of boost pressure, sluggish acceleration, Blue smoke from exhaust on startup or acceleration, Whining or grinding noise from engine bay, Check engine light with underboost codes

Fix: V12 layout means tight access. Each turbo is 8-12 hours labor due to subframe work and exhaust manifold removal. If one turbo fails from oil contamination (common with bearing debris), the other often follows within 10k miles. Smart move is replacing both plus all oil feed/return lines.

Estimated cost: $8,000-16,000

Typical onset: 70,000-110,000 mi

Symptoms: Transmission fluid puddles under car (red fluid), Burnt transmission fluid smell, Harsh shifting or slipping when fluid is low, Transmission overheat warnings on dash

Fix: The external cooler lines corrode where they connect to the radiator and transmission. Line replacement is straightforward (3-5 hours), but often the cooler itself is leaking internally into the radiator, contaminating coolant. That requires radiator replacement and full fluid flush of both systems. Add 2-3 hours if doing radiator.

Estimated cost: $1,200-2,800

Typical onset: 80,000-130,000 mi

Symptoms: Car drops to bump stops overnight or after sitting, ABC warning light with 'car too low' message, Green hydraulic fluid puddles (distinct smell), Harsh ride quality, inability to raise suspension

Fix: Leaks typically from front struts, pressure hoses, or the tandem pump. Front struts are 6-8 hours each. Pump replacement is 8-10 hours. Hydraulic hoses can nickel-and-dime you — there are dozens, and once one fails, others follow. System holds 7+ liters of fluid at $40/liter. Budget for multiple repairs over ownership.

Estimated cost: $2,500-7,000

Typical onset: 90,000-150,000 mi

Symptoms: Harsh or delayed shifts, especially 2-3 and 3-4, Transmission slipping or refusing to engage gears, Limp mode (stuck in one gear), Multiple transmission fault codes stored

Fix: The 722.9 7-speed transmission's valve body wears internally, and the conductor plate (electrical control module inside the pan) corrodes. Valve body replacement requires transmission removal on the V12 due to space constraints — 12-16 hours labor. Conductor plate alone is 6-8 hours if that's the only issue, but it rarely is by this mileage.

Estimated cost: $4,500-8,500

Typical onset: 60,000-100,000 mi

Symptoms: Vibration at idle, especially in Drive with brake on, Clunk when shifting from Park to Drive or Reverse, Excessive engine movement visible when revving

Fix: The V12's weight destroys mounts faster than V8 models. All four typically need replacement together. Front two are 2-3 hours each; rear two are 1.5-2 hours each due to better access. Total 8-10 hours for all four. Not difficult, just time-consuming because of the engine size.

Estimated cost: $2,000-3,200

Typical onset: 90,000-140,000 mi

Symptoms: Suspension warning light, 'Airmatic Visit Workshop', One corner sags overnight (strut leak), Compressor runs constantly or won't run at all, Rough ride, bottoming out over bumps

Fix: Note: W221 S600 has ABC, not Airmatic on base models — but some markets got Airmatic. If equipped, compressor is 3-4 hours, each strut is 2-3 hours. ABC struts (see problem #4) are hydraulic and more expensive. Verify your system before ordering parts.

Estimated cost: $1,800-4,500