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2018 PORSCHE 911

3.0L Twin Turbo H6•RWD•DCT•gas•MDG.1A•turbo
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5-Year Cost of Ownership
$22,121 maintenance + known platform issues
~$4,424/yr · 370¢/mile equivalent · $7,816 maintenance + $11,705 expected platform issues
Compare this engine
vs
3.8L H6
vs
3.4L H6
Common Problems & Known Issues

The 991.2-generation 911 (2017-2019) is generally reliable, but the carryover naturally-aspirated engines (3.4L/3.8L in base/S models through mid-2016) can suffer catastrophic bore scoring, while the newer 3.0L twin-turbo (Carrera/S from late 2016+) has proven far more durable. Transmission cooling and mount issues are nuisances but manageable.

Cylinder Bore Scoring (3.4L/3.8L NA engines only)

Occasional · high severity
Typical onset: 40,000-80,000 mi
Symptoms: excessive oil consumption (>1qt per 1,000 mi), cold-start smoking, loss of compression, metallic rattling at idle
Fix: Complete engine rebuild or replacement. Requires engine-out, cylinder resleeve or new block, pistons, rings, bearings. 40-60 labor hours depending on shop familiarity. Some owners opt for LN Engineering sleeved blocks as preventive measure.
Estimated cost: $18,000-30,000

Transmission Oil Cooler Leaks (PDK models)

Common · medium severity
Typical onset: 50,000-90,000 mi
Symptoms: transmission fluid puddles under car, low fluid warning on dash, burnt fluid smell, harsh shifts when hot
Fix: Replace cooler lines and/or cooler assembly. Access requires partial undertray removal and sometimes exhaust work. 3-5 labor hours plus fluid refill and adaptation procedure.
Estimated cost: $1,200-2,200

Transmission Mount Failure (all models)

Common · low severity
Typical onset: 60,000-100,000 mi
Symptoms: clunking on hard acceleration or deceleration, excessive driveline vibration, visible tearing in rubber mount
Fix: Replace transmission mount. Car must be lifted, transmission supported, old mount unbolted. 2-3 labor hours. OEM part recommended over aftermarket.
Estimated cost: $600-1,000

Fuel Filter Clogging (track-driven cars)

Occasional · medium severity
Symptoms: stumbling under sustained high-RPM load, limp mode on track, fuel trim adaptation faults, lean codes
Fix: Replace in-tank fuel filter assembly. Requires fuel tank drop or rear seat removal for access depending on model. 2-4 labor hours. More common in cars using lower-grade fuel or tracking frequently.
Estimated cost: $800-1,400

Coolant Expansion Tank Cracking (3.0L turbo)

Occasional · medium severity
Typical onset: 70,000-110,000 mi
Symptoms: coolant smell in cabin, visible coolant seepage on tank, low coolant warning, steam from engine bay
Fix: Replace plastic expansion tank and cap. Access is tight but doable without major disassembly. 1.5-2.5 labor hours including system bleed.
Estimated cost: $500-900

Rear Main Seal Seepage (all engines)

Occasional · low severity
Typical onset: 80,000-120,000 mi
Symptoms: oil drips from bell housing area, oil accumulation on undertray, no active leaking while running, seeps when parked
Fix: Requires transmission removal to access seal. 12-16 labor hours. Often deferred until clutch replacement on manuals or other transmission work on PDK.
Estimated cost: $2,200-3,800
Owner tips
  • If buying a 2016-early 2017 base/S, verify it has the 3.0L turbo (991.2) not the 3.4L/3.8L (991.1 carryover). Check build date, not model year.
  • Get a pre-purchase borescope inspection on any NA engine to check for bore scoring before purchase—catching it early can save $20k+.
  • PDK fluid and filter should be changed every 40,000 mi despite Porsche calling it 'lifetime'—prevents valve body and cooler issues.
  • Maintain meticulous service records; Porsche CPO and extended warranty won't cover bore scoring if oil changes aren't documented every 10k mi.
  • Track-driven cars should have fuel filter replaced every 30,000 mi regardless of symptoms.
Excellent used buy if it's a 2017+ with the 3.0L turbo and full service history; avoid 2016 models with NA engines unless bore scoring has been professionally ruled out.
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.
492 jobs across 17 categories

body (31)

brakes (36)

cooling (21)

drivetrain (24)

electrical (75)

engine (71)

exhaust (23)

hvac (23)

interior (24)

maintenance (31)

suspension (42)

transmission (42)

🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years.
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