The 2015 Q70 is Infiniti's executive sedan built on the proven FM platform, sharing DNA with the 370Z and G37. While generally reliable, the V6 engines have a critical oil consumption defect, the 7-speed automatics suffer cooler failures, and the hybrid variant brings added complexity most shops can't handle economically.
VQ37VHR Engine Oil Consumption / Piston Ring Failure (3.7L V6)
Common · high severityTypical onset: 60,000-110,000 mi
Symptoms: Burning 1+ quart every 1,000-2,000 miles with no external leaks, Blue smoke on cold starts or hard acceleration, Check engine light for catalyst efficiency codes (P0420/P0430), Oil residue coating spark plugs during inspection
Fix: Nissan's piston ring design allows oil scraping past worn rings. Proper fix is engine rebuild with updated rings or short block replacement. TSB NTB13-083a documents this but Nissan won't warranty beyond 60k. Expect 25-35 hours labor for rebuild, 18-22 hours for short block swap.
Estimated cost: $5,500-8,500
Transmission Oil Cooler Line Corrosion (All models)
Common · high severityTypical onset: 70,000-120,000 mi
Symptoms: Transmission fluid leaking from cooler lines at radiator, Pink fluid pooling under front of vehicle, Sudden transmission slipping or delayed engagement if fluid level drops critically, Potential cross-contamination into coolant system causing milky appearance
Fix: Steel cooler lines rust through where they run along subframe, especially in salt states. Must replace both lines and flush transmission if contamination occurred. If coolant mixed into trans, cooler and radiator replacement also required. 4-6 hours labor for lines only, 12-15 hours if contamination cleanup needed.
Estimated cost: $800-1,200 (lines only), $3,500-5,000 (with contamination)
Transmission Mount Failure (All models)
Occasional · medium severityTypical onset: 80,000-130,000 mi
Symptoms: Clunking when shifting from Park to Drive or Reverse, Excessive vibration at idle in Drive with brake applied, Visible separation or oil weeping from mount during inspection, Shifter hesitation or hard engagement into gear
Fix: Hydraulic transmission mount deteriorates from heat and age. Common on all Nissan/Infiniti RWD platforms. Replacement is straightforward but requires supporting powertrain. 2.5-3.5 hours labor. Replace engine mounts at same time if showing wear to save future labor.
Estimated cost: $450-750
VQ35HR Hybrid System Battery Degradation (3.5L Hybrid only)
Occasional · medium severityTypical onset: 100,000-150,000 mi
Symptoms: Reduced electric-only range or EV mode won't engage, Master warning light with hybrid system fault codes, Frequent engine cycling even with sufficient battery charge, Diagnostic shows individual cell imbalance or capacity loss below 70%
Fix: Lithium-ion traction battery degrades over time. Infiniti offers no individual cell replacement—entire battery pack required at dealer-only pricing. Most independent shops won't touch hybrid system due to high-voltage certification requirements. 6-8 hours dealer labor plus $4,000-6,000 parts.
Estimated cost: $6,500-9,000
Fuel Filter Clogging from Tank Debris (All models)
Occasional · medium severityTypical onset: 90,000-140,000 mi
Symptoms: Hesitation or stumbling under acceleration, especially when tank below 1/4, Hard starting after sitting, improves after cranking several times, Check engine light with lean fuel mixture codes (P0171/P0174), Loss of power on highway pulls or uphills
Fix: In-tank fuel filter clogs from sediment, common on higher-mileage units that weren't maintained with quality fuel. Filter is part of pump assembly, requires tank drop. Some techs clean existing filter if caught early. 3-4 hours labor. Recommend full pump assembly replacement if pump shows wear.
Estimated cost: $600-1,100
Driveshaft Center Support Bearing Wear (RWD models)
Occasional · medium severityTypical onset: 90,000-150,000 mi
Symptoms: Vibration at highway speeds (60-75 mph) that intensifies with acceleration, Clunking or grinding noise from underneath during throttle changes, Rumbling sound that changes with vehicle speed, not engine RPM, Visible play in driveshaft when inspecting on lift
Fix: Two-piece driveshaft uses center support bearing that wears from age and heat. NHTSA recall 15V-377 covered some units for propshaft imbalance. Replacement requires driveshaft removal and pressing new bearing. 2.5-3.5 hours labor. Some shops replace entire driveshaft assembly if U-joints also worn.
Estimated cost: $500-850
Buy the 3.7L V6 only if prior owner can document oil consumption was monitored and addressed; otherwise stick to low-mileage examples under 60k or budget for an engine rebuild—skip the hybrid unless buying under warranty.
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.