Subaru Legacy BN

Subaru's volume boxer: 2.5L NA in Legacy, Outback, Forester. Oil consumption class action for 2011-2014 models — piston rings didn't seat properly. Cam carrier seal leaks from ~60k miles (labor-intensive). Thermo control valve on 2019-2022 models: plastic housing fails under heat — Subaru extended warranty to 15 years. Improved from 2023.

• !! Oil Consumption — Piston Rings (2011-2014) from 40,000 km

  Class action for 2011-2014 Forester, Legacy, Outback. Piston rings didn't seat due to variable bore roughness. Worst cases: 1 quart per 800 miles.

  Symptoms: Extreme oil consumption, frequent top-ups needed, blue smoke possible
  4,000–6,000 $
  Ad 12033AB340 piston ring set FB2510103AB330 short block FB25piston rings Subaru FB25
• !! Cam Carrier Seal Leak from 100,000 km

  Known FB engine problem: seal between cam carrier and cylinder head fails. Labor-intensive due to poor access. Service bulletins published.

  Symptoms: Oil stain under engine, oil smell while driving, visible oil seepage at cylinder head
  1,700–6,000 $
  Ad 13270AA29A valve cover gasket right FB2513272AA24A valve cover gasket left FB2510966AA041 spark plug tube sealcam carrier seal Subaru FB25
• !! Thermo Control Valve Failure (2019-2022) from 60,000 km

  Electronic TCV plastic housing fails above 200°F. All warning lights simultaneously (EyeSight, front collision). Warranty extended to 15 years/150k miles. Mechanical thermostat replaces TCV from 2023.

  Symptoms: All warning lights at once, no heater, fault codes P2682/P26A3/P26A5
  1,300–1,800 $
  Ad 21200AA270 thermo control valve FB25TCV Subaru Forester Outbackthermo control valve Subaru FB25

+ 1 more engine weaknesses + vehicle weaknesses

Six-cylinder boxer: 3.6L naturally aspirated, smooth and torquey. Significantly more reliable than the EJ four-cylinders. Oil leaks at valve covers and timing chain cover at higher mileage are the main concerns. No head gasket issues. 200k+ mile lifespan realistic.

• !! Timing Chain Tensioner Worn from 150,000 km

  Plastic timing chain tensioner wears after 90,000+ miles and can no longer maintain adequate chain tension. Starts with cold-start rattle, can progress to timing chain jump. Expensive repair due to many bolts on the chain cover.

  Symptoms: Rattling on cold start, loud chain noise, misfires at high mileage
  1,500–3,200 $
  Ad 13142AA090 timing chain tensioner EZ36timing chain tensioner Subaru H6 EZ36timing chain kit Subaru 3.6R
• ! Oil Leaks at High Mileage from 120,000 km

  Valve cover gaskets and timing chain cover become leaky at higher mileage. Typical for boxer engines with many sealing surfaces. Not a critical weakness, but noticeable cosmetically and by smell.

  Symptoms: Oil spots under engine, oil smell when engine is hot
  800–2,000 $
  Ad 13270AA29A valve cover gasket right EZ3613272AA24A valve cover gasket left EZ36valve cover gasket Subaru H6 EZ36
• ! Serpentine Belt Tensioner Worn from 130,000 km

  Belt tensioner spring fatigues after approximately 75,000-95,000 miles. Loss of tension causes slipping, squealing, and in severe cases, failure of the alternator and A/C compressor.

  Symptoms: Squealing from engine bay, A/C failure, battery warning light, overheating
  250–400 $
  Ad 23769AA010 belt tensioner EZ36serpentine belt tensioner Subaru H6 EZ36drive belt tensioner Subaru 3.6R