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2018 PORSCHE 911

3.0L Twin Turbo H6•RWD•DCT•gas•turbo
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5-Year Cost of Ownership
$22,350 maintenance + known platform issues
~$4,470/yr · 370¢/mile equivalent · $8,045 maintenance + $11,705 expected platform issues
Compare this engine
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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.
539 jobs across 17 categories
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Lexus & Toyota Mechanic · 20+ years.
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