Subaru STI
The STI engine — 2.5L turbo boxer with rally heritage and the most notorious piston problem in automotive history. Cast iron ringlands crack under detonation, especially with poor fuel or aggressive tuning. Community estimate: under 0.1% failure rate on maintained stock cars — but the stigma sticks. Stronger factory pistons from 2019, no fundamental redesign. Unequal-length headers create the iconic boxer rumble: an asymmetric burble no other four-cylinder can reproduce. 93 octane mandatory. Reliable to ~350 whp, above that it's forged internals or engine failure.
Last STI — 310 hp EJ257, no successor. Period.
The final EJ257 STI: no VB successor in sight. DCCD, manual, boxer rumble — everything that became history after 2021. 2019+ with stronger factory pistons: ringland risk reduced. Used prices exploded after the "no VB STI" announcement. S209 (209 units): $80-107k. Regular VA STI: $35-55k. Community: "If you have a mint VA STI, keep it."
Engine Weaknesses 5
THE EJ257 topic: stock cast iron pistons crack under detonation. 93 octane mandatory, no aggressive tuning without forged internals. Stronger pistons from 2019, but no fundamental redesign. Reliable to ~350 whp stock.
Symptoms: Misfires at idle after full throttle, blue smoke, rapidly increasing oil consumption, compression loss
Class action settlement: 2012-2017 WRX/STI with warranty extension to 8 years. Oil starvation from boxer sloshing during aggressive cornering as primary cause.
Symptoms: Knocking from the block, dropping oil pressure, metal shavings in oil filter
Brazed joint cracks from vibration — identical across all EJ engines. Aftermarket reinforcements available (IAG). Subaru refuses to issue a recall.
Symptoms: Sudden oil pressure drop without warning, engine noise
Timing belt replacement every 105k miles mandatory. For a track-used STI, shorter intervals recommended.
Boxer engine with flat oil pan: under high lateral G-forces, oil sloshes away from the pickup. Track use without baffled sump or air-oil separator significantly increases bearing failure risk.
Symptoms: Oil pressure drop in fast corners, oil temperature spikes
Vehicle Weaknesses 5
Known STI issue across all generations: galvanic corrosion between steel bolt and aluminum caliper. Copper anti-seize on installation prevents the problem. VA retains 6-piston Brembo front.
EyeSight camera system detects phantom obstacles and brakes automatically — particularly dangerous at highway speeds. Class action settlement for 2016-2021 STI.
TSB 05-61-16 applies to the VA STI. Strut mounts wear early — some cars clunk under 5,000 miles. Subaru updated part number to address the issue.
Class action settlement for 2015-2020 WRX/STI: CAN bus won't go to sleep, excessive parasitic draw. Battery drains after a few days parked.
TSB 03-74-14: DCCD rear differential breather vent not correctly installed — gear oil leaks out and can drip onto the exhaust pipe.