About the Subaru 2.5 Engine
A versatile vehicle engine, the Subaru 2.5 is a very reliable workhorse that has powered an endless number of adventures. It is known for its strength in terms of workability and smooth operation. Performance without fuel squandering capabilities makes it good for both road and rough-road drives. The flat design of the engine ensures that the center of gravity for the vehicle is low, which adds character to its stability and handling. Well-kept, this Subaru 2.5 engine for sale here will deliver hundreds of thousands of miles.
So, if a Subaru Forester, Outback, Legacy, Crosstrek, or Ascent owner wishes to give their vehicle a breath of fresh air, a quality used 2.5 engine is a great investment. Its reputation for reliability and versatility has earned it widespread praise from Subaru aficionados.
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>Overview of the Subaru 2.5 Engine: Two Engine Families>
The Subaru 2.5 has been produced in two distinct engine families across its production history. Understanding which family you need is important for proper fitment: FB25 (2011-Present), Current Generation Subaru's current 2.5L boxer engine, introduced in 2011 to replace the older EJ25 NA in standard Subaru vehicles.
What's the difference between FB25 and EJ25?
Two different engine families covering Subaru's 2.5L NA boxer applications across different model years: | Feature | EJ25 NA (Older) | FB25 (Current) | | --- | --- | --- | | Years | 1995-2013 | 2011-present | | Bore x Stroke | 99.5 x 79 mm | 94 x 90 mm | | Valvetrain | SOHC | DOHC | | AVCS | Limited | Standard (intake + exhaust) | | Block Design | Open-deck (head gasket prone) | Semi-closed deck (improved) | | HP | 165-173 HP | 170-185 HP | | Head Gasket Service | Common service item | Far less common | | Common Applications | Pre-2014 Forester/Outback/Legacy/Impreza | Forester 2014+, Outback 2010+, etc. | The FB25 is a clean-sheet redesign that addresses many of the EJ25's known service items, particularly head gaskets.
Which Subaru models use which engine?
FB25 (current 2011+): Forester (2014+ 4th gen, 2019+ 5th gen) Outback (2010+ 5th gen, 2020+ 6th gen) Legacy (2010+ 6th gen, 2020+ 7th gen) Crosstrek (2018+ 2nd gen) Some Ascent variants (2019+) EJ25 NA (older 1995-2013): Pre-2014 Forester, Outback, Legacy 2.5L Impreza (1996-2011) Baja (2003-2006)
Are FB25 and EJ25 interchangeable?
No, not directly interchangeable. Major differences: Different bell housing patterns for transmission mating Different ECU programming , each engine has unique fuel maps Different accessory drives and engine mounts Different intake/exhaust manifold configurations When replacing a Subaru 2.5, you need the same engine family as the one being replaced. We confirm variant identification before shipping.
What's the FB25 oil consumption issue?
Known service item on 2011-2014 FB25 engines. Some early FB25 engines develop higher-than-normal oil consumption, often beginning at 60,000-100,000 miles. The cause was related to piston ring design. Symptoms: Oil level dropping between changes, blue smoke under acceleration, fouled spark plugs Subaru response: Extended warranty coverage on affected engines, offered piston ring replacement Service: Piston ring replacement (a major engine service requiring engine removal) Verify: When buying any 2011-2014 FB25, verify any piston ring service was performed Later FB25 engines (2015+) addressed the issue with revised piston rings and oil control.
What's the EJ25 head gasket issue?
The most famous Subaru reliability story. EJ25 NA SOHC engines (EJ251, EJ253) develop head gasket failures at 100,000-150,000 miles. The cause: Open-deck aluminum block design allows minor flex under thermal cycling Original head gasket material didn't handle the long-term cycling well Result: External coolant leaks (most common) or oil-coolant cross-contamination Subaru response: Extended warranties on affected models, updated multi-layer steel (MLS) head gaskets for repair, eventually redesigned the engine into the FB25 with semi-closed deck. Service cost: $1,500-3,000 for proper repair with MLS gaskets, typically fixes the issue permanently.
How long does the Subaru 2.5 typically last?
With proper maintenance: FB25: Well-maintained: 250,000+ miles achievable 2011-2014 with oil consumption service done: Standard FB25 longevity Without oil consumption service: May see piston ring issues at 100,000-150,000 miles EJ25 NA: Without head gasket service: 100,000-150,000 miles to typical failure With head gasket service (MLS gaskets): 200,000+ miles common Well-maintained Outbacks with serviced EJ25: 300,000+ miles documented Maintenance is critical for both families.
Does the Subaru 2.5 need premium fuel?
No, regular 87 octane is acceptable for both naturally aspirated 2.5L families (FB25 and EJ25 NA). Subaru's 2.5L NA engines are designed for regular fuel. Note: Some 2018+ direct-injected FB25 variants benefit from 89 octane mid-grade in hot weather or under load, but 87 remains acceptable. Only the turbocharged EJ255, EJ257, and FA20DIT require premium , the NA 2.5 engines do not.
How much does a used Subaru 2.5 engine typically cost?
Pricing varies by family and condition: | Variant | Used Engine Cost | Reman Cost | New Crate | | --- | --- | --- | --- | | FB25 (current) | $1,200-3,500 | $3,500-5,500 plus core | $6,500-9,500 plus core | | EJ25 NA SOHC | $1,000-2,500 | $2,500-4,000 plus core | Generally not available new | Our $1,499 pricing represents excellent value for either family in tested working condition with full inspection.
