Owners report a dominant pattern of piston ringland failures—cracked or broken ringlands predominantly on pistons #2 and #4—occurring anywhere from 1,200 to 33,000 miles. Symptoms include white smoke on cold startup, loss of power at low RPM and under light throttle, rough idle, excessive oil consumption, and dramatic power loss under acceleration. Compression tests show cylinder pressure drops (one owner documented cylinder #4 at 100 psi vs. 115–125 psi on others; another saw #4 at 50–70 psi, far below spec). Several owners report the failures are nearly impossible to detect without tear-down—one noticed only mild degradation while running on 3.5 cylinders. Ringland breakage leads to severe blowby, fuel in the oil, and if left unchecked, engine seizure that can happen in minutes during aggressive driving. One owner's engine seized mid-maneuver, creating an oil slick hazard. Dealers initially struggled to diagnose the problem; one owner brought his car in multiple times before ringland failure was found. Some owners suspect detonation sensitivity tied to aggressive OEM tuning combined with weak cast pistons. Additional engine issues include oil leaks from head gaskets and valve covers (one repaired under NHTSA campaign 08V460000 but recurred), connecting rod bearing failures, and cold-start stalling due to dropped RPM to zero during warm-up in cold weather. One owner reported rough idle, engine shudder, and immediate shutdown when accelerating, though the dealer found only a leaking valve. Low-mileage failures dominate the complaints, with several occurring under 20,000 miles despite full oil changes and regular maintenance.
Failure modes owners describe
Piston ringland failure
Cracked or broken ringlands on pistons (most commonly #2 and #4) causing compression loss, blowby, and oil consumption. Owners report Subaru initially denied widespread problem despite internet forums showing many affected vehicles. Some failures occurred after engine replacement under warranty, suggesting design defect.
When: 1,200 to 33,000 miles
Symptoms owners cite: White smoke on cold startup; Power loss at low RPM and under light throttle; Rough idle; Excessive oil consumption; Stumbling at 3,000 RPM; Dead spots in power band throughout RPM range; Loss of acceleration
Codes mentioned: P0301, P0302, P0303, P0304
Repairs/costs cited: Bottom end or short block replacement; one owner paid partial cost under goodwill repair before ringland failure was confirmed. Cost not documented. One piston was replaced at private shop after dealer refused compression test.
Recalls/TSBs owners mention: Subaru issued a stop sale on some 2008 WRX models; some owners received goodwill repairs. One owner reported dealership refused warranty claim citing lack of maintenance records. NHTSA campaign 08V460000 addressed some engine issues. Subaru told some owners the car runs as designed.
Head gasket leak
Premature head gasket failure allowing oil to leak onto hot engine surfaces, creating fire hazard. One owner cited incorrect factory gasket sizing as root cause. Leaks recurred within two weeks of initial dealer repair in at least one case.
When: Varies; one recurrence at 119,000 miles after prior repair
Symptoms owners cite: Oil leaking from engine; Smoke coming from front of vehicle; Oil film on windshield
Repairs/costs cited: Valve covers initially replaced, then oil return line clamps; ultimately oil feed line replacement required. Repair cost exceeded $2,000 in one case.
Recalls/TSBs owners mention: Repaired under NHTSA campaign 08V460000 (Engine and Engine Cooling) in one case; however, failure recurred post-repair and dealer could not diagnose or repair the second occurrence.
Engine seizure due to oil loss
Complete engine stoppage caused by severe oil loss from blowby related to ringland failure or bearing degradation. Can occur within minutes during aggressive driving, creating sudden loss of power on highway.
When: As early as 77,000 miles; can occur minutes after symptom onset
Symptoms owners cite: Engine knocking; Power loss; Squealing; Engine will not restart
Repairs/costs cited: Complete engine replacement required; one owner quoted $10,000 replacement cost at 77,000 miles.
Connecting rod bearing failure
Rod bearing failure on crankshaft causing knocking, shaking, and running poorly. One owner experienced this as a follow-up issue after initial ringland repair. Appears tied to debris from ringland failures or underlying engine assembly defects.
When: At 79,000 miles on one vehicle; shortly after ringland repair on another
Symptoms owners cite: Knocking noise from engine; Shaking and clicking; Running poorly; Power loss
Repairs/costs cited: Engine long block replacement required.
Recalls/TSBs owners mention: One owner received re-manufactured engine for warranty repair, which owner objected to since vehicle came with factory engine.
Cold-start rough idle and stalling
RPM drops to zero during warm-up period in cold weather, causing engine stall when clutch is depressed to shift. Occurs consistently and creates loss of power steering and power braking mid-maneuver.
When: Early in ownership; 22,500 miles on one vehicle
Symptoms owners cite: RPM drops to zero during warm-up; Engine stalls when depressing clutch; Loss of power steering; Decreased power braking; Engine vibration and rumbling on startup
Codes mentioned: P0301, P0302, P0303, P0304
Repairs/costs cited: Dealership attempted repair multiple times (three visits documented in one case) without finding root cause.
Engine vibration and rumbling on startup
Vibration and rumbling every time vehicle is started. Dealer inspection found nothing wrong in one case.
When: Present from purchase
Symptoms owners cite: Engine vibration; Engine rumbling on startup
Recalls/TSBs owners mention: Dealer found no issue.
Oil leaking from valve cover
Oil seepage from valve covers, with recurrence even after initial repair.
When: At 119,000 miles on one vehicle
Symptoms owners cite: Oil leaking from engine; Smoke from front of vehicle
Repairs/costs cited: Valve covers replaced; failure recurred.
Engine shutdown under acceleration
Engine shuts down immediately when accelerator is pressed, accompanied by loud shudder. Lights remain on; vehicle restarts immediately. Occurred twice in one documented case.
When: Early in ownership
Symptoms owners cite: Loud shuddering; Immediate engine shutdown; Vehicle restarts without issue
Repairs/costs cited: Dealer could not duplicate problem but found leaking valve covered under warranty.
Synthesized from 29 NHTSA owner complaints — unverified consumer
allegations, summarized for patterns. The verbatim filings appear below.