The 2018 Forester (fourth-gen FB25 engine) is generally reliable but suffers from oil consumption issues that can escalate to catastrophic engine failure if ignored. The CVT is more durable than prior generations but cooler lines and mounts still need attention.
Excessive Oil Consumption Leading to Engine Failure
Common · high severityTypical onset: 60,000-120,000 mi
Symptoms: Low oil warning light comes on between changes, Blue smoke from exhaust on startup or acceleration, Requires 1+ quart top-off every 1,000-2,000 miles, Sudden engine knock or seizure if oil runs critically low
Fix: FB25 engines burn oil through piston rings and valve guides. Subaru extended warranty to 8yr/100k for this, but outside that window you're looking at piston ring replacement (12-15 hrs labor, engine-out preferred) or short block swap (18-22 hrs). If spun bearings or seized, full rebuild or used engine. Monitor oil religiously every 500 miles.
Estimated cost: $4,500-8,000
CVT Transmission Oil Cooler Line Leaks
Occasional · medium severityTypical onset: 70,000-110,000 mi
Symptoms: Transmission fluid drips under vehicle, near front, Low CVT fluid warning or limp mode, Transmission overheating message on long highway drives
Fix: Rubber cooler lines to the external cooler crack at crimp points. Replace both lines (Subaru updated parts available), flush CVT fluid. 2-3 hrs labor. Catch it early before running low causes CVT belt slip damage.
Estimated cost: $400-700
Transmission Mount Failure
Common · low severityTypical onset: 80,000-130,000 mi
Symptoms: Clunk or thud when shifting from Park to Drive or Reverse, Excessive vibration at idle, Visible sag or cracking in rear transmission crossmember mount
Fix: Rear trans mount rubber deteriorates. Replace mount (OEM or upgraded aftermarket polyurethane). 1.5-2 hrs labor. Not safety-critical but annoying and can stress driveline components.
Estimated cost: $250-450
Head Gasket Seepage (Minor, FB25)
Occasional · medium severityTypical onset: 100,000-150,000 mi
Symptoms: Small external oil weep at head/block seam, Slight coolant smell but no mixing into oil, White residue around head bolt area
Fix: FB25 is far better than EJ engines, but some units still weep externally. If caught early and no coolant-oil mixing, you can defer, but full head gasket replacement is 12-14 hrs labor (both sides). Don't confuse with oil consumption issue—this is seam leakage.
Estimated cost: $2,200-3,500
Fuel Pump Failure (Recall-Related)
Rare · high severitySymptoms: Engine stalls while driving, no restart, Intermittent no-start, cranks but won't fire, Loss of power at highway speed
Fix: NHTSA recall for low-pressure fuel pump impeller cracking. If not done, get recall serviced (free at dealer). If post-recall failure, pump replacement is 2-3 hrs labor. Can strand you but rarely happens if recall completed.
Estimated cost: $600-1,000
Front Wheel Bearing Noise
Occasional · medium severityTypical onset: 80,000-120,000 mi
Symptoms: Humming or growling noise that changes with speed, Noise louder in turns (inside or outside bearing depending), Vibration through steering wheel at highway speed
Fix: Hub/bearing assembly replacement, one side at a time. 2-2.5 hrs per side. Not unique to Forester but common enough on AWD Subarus in salt states. Replace in pairs if both sides noisy.
Estimated cost: $400-650 per side
Solid choice if oil consumption history is documented and CVT has been maintained; avoid high-mileage examples with no service records or low-oil history.
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.