When people think about Subaru, they often picture reliability, ruggedness, and that distinctive boxer engine sound.
Yes, the Subaru 3.6 (EZ36) is a strong and reliable engine. It delivers good power, smooth performance, and above-average reliability, making it one of Subaru’s most dependable six-cylinder options for long-term use.
In this article, we’ll break down its real-world reliability, performance, common problems, and whether it’s the right choice for you.
Specifications & Design Overview
At its core, the EZ36 is a 3.6-litre (3,629 cc) horizontally-opposed (boxer) six-cylinder engine. Here are some of the key design figures:
- Displacement: 3,629 cc (3.6 L)
- Bore × stroke: approx 92.0 mm × 91.0 mm
- Compression ratio: ~10.5:1 in many markets.
- Maximum output: around 256 hp @ ~6,000 rpm and 247 lb-ft (≈335 Nm) of torque.
- Aluminium block & heads, DOHC 24-valve, with the boxer layout giving a lower centre of gravity.
Why does the layout matter? A flat-six engine sits lower in the chassis compared to a tall inline-six or V6, which helps the vehicle’s handling and balance.
The boxer architecture also tends to cancel out some vibration inherently. These aspects enhance driving feel and stability, and are part of why many Subaru fans favour the 3.6 over simply going for “more cylinders = more trouble”.
Real-World Reliability and Longevity
On paper and in the driving seat, the EZ36 shows strong traits. But reliability depends heavily on how the car has been looked after.
Owner forums and independent reviews suggest many examples have passed 180,000 miles (≈290,000 km) and beyond with few major issues. For instance: “With proper maintenance the engine shouldn’t have any issues surviving beyond 200,000 miles” is a comment you’ll see in reliability guides.
Here are some bullet points worth noting:
- Many owners report trouble-free usage when the oil is changed regularly, cooling service is kept, and the belt/pulley/tensioner group is inspected.
- The design improvements over the earlier EZ30 engine (which preceded it) are often cited: improved cooling, refined internal components, and fewer of the chronic issues that the older engine had.
- Because it’s naturally aspirated (no turbo), it avoids some of the forced-induction wear issues and associated cost that some high-performance engines carry.
So yes, for many users the 3.6 is a “good engine” in the sense of being durable, solid and offering a refined experience. But the caveat remains: maintenance matters.
Also Read: Subaru Crosstrek USB Port Not Working: Quick Fixes & Causes
Common Problems & Known Weak Points
No engine is flawless, and the EZ36 does have recurring issues—though many are manageable if caught early and addressed. Knowing these will make your article more balanced and will help buyers avoid surprises.
Oil leaks & oil consumption
Oil leaks are fairly common in engines with some age and use. The EZ36 is not immune. Some of the leak paths include the valve cover gaskets, oil pan gasket, timing cover and other seals.
See this reliability review: “The engine life is about 180,000 miles … but the area of the 3.6 engine that requires sealing means leaks are even more likely.” Some owners also report higher oil consumption—meaning they need to top up between changes.
Belt tensioner, serpentine belt & timing chain tensioner
Although the timing chains themselves are generally reliable, components like the timing chain tensioner and the serpentine belt tensioner/pulleys appear more often in trouble reports.
For example: “The spring within the tensioner wears down… the EZ36 belt tensioner spring may ‘bounce’ around under engine load.” While these issues aren’t catastrophic, they can lead to accessory failures, belt failures, and ultimately affect reliability.
Cooling system / head gasket (less common)
While much less frequent than in older Subaru six-cylinder engines, cooling system issues—overheating, coolant leaks—and head gasket problems occasionally crop up. Regular coolant system maintenance is wise.
Fuel economy & running costs
Because it’s a six-cylinder naturally aspirated engine, fuel economy is not its strong suit. One article notes combined mileage around 16-18 mpg (≈13-15 L/100 km) in some usage. If you’re comparing with smaller turbo-four or modern efficient engines, you’ll pay more at the pump.
So summarising: the engine has known weak points, but none of them appear to be “killer defects” when properly maintained. The key is inspection, regular service, and being alert to early symptoms.
Performance & Driving Experience
What many buyers value about the 3.6 engine is not just its reliability but how it feels on the road. In the cars it powers, the engine offers smooth, strong performance with a character that matches Subaru’s all-wheel-drive and outdoors-oriented image.
The torque figure (~247 lb-ft) means you get good low-to-mid rpm pull, which is helpful for overtaking, highway merging or moderate towing tasks.
The boxer layout gives a distinctive smooth sound and low vibration feel. According to spec sheets, the engine produces around 256 hp @6,000 rpm and torque at ~4,400 rpm.
In vehicles like the Outback or Legacy with the 3.6-litre, the extra cylinders make them feel more refined than the base 2.5-litre versions—especially when loaded, or in uphill / hilly terrain. That can be a strong selling point if you value smooth driving and stronger performance rather than just economy.
Fuel Economy and Maintenance Costs
As noted, the fuel economy of the 3.6-litre naturally aspirated engine will lag behind efficient four-cylinders or downsized turbo engines. One guide puts combined mileage in the neighbourhood of 16-18 mpg (≈13-15 L/100 km) under some conditions.
On the maintenance side:
- Oil changes: Using high quality synthetic oil and keeping up with change intervals is important. Owner guides recommend synthetic 5W-30 (or similar) and checking oil level regularly.
- Belt/tensioner replacement: Since the accessory belt and tensioner is flagged as one of the recurring items, budget for inspection and possible replacement around high-mileage. For example: “Serpentine belt tensioner … parts $100-150, labour $150-250.”
- Cooling system service: Coolant flushes, hose inspections and head gasket inspection should be part of the schedule.
- Parts availability: Since six-cylinder Subaru engines are less common than the four-cylinders globally, in some regions parts might be less ubiquitous or more costly.
In short, it’s not prohibitively expensive to maintain, but you’ll want to budget more than you would for a standard four-cylinder, especially if the car has higher miles.
Must Read: Will Dodge 5 Lug Fit Chevy 5 Lug – Complete Review!
Is the Subaru 3.6 a Good Engine for You? (Pros & Cons)
Here’s a quick look at the main advantages and trade-offs to help determine if this engine suits your needs.
Pros
- Strong performance: The six cylinders provide smoother power delivery and better refinement than many four-cylinders in the same class.
- Good longevity: Many owners report comfortable mileage with few major problems provided maintenance is done.
- Handling benefit: The boxer layout gives a lower centre of gravity and better balance, which helps driving feel—especially for AWD/crossover usage.
- Versatility: The engine can handle different driving conditions—daily commute, family duty, even moderate towing or off-pavement work.
Cons
- Fuel economy: It won’t beat modern efficient four-cylinders or turbo engines for consumption.
- Maintenance vigilance: While no major “design flaw” is prevalent, you must stay on top of leaks, belts/tensioners, and cooling system components.
- Higher parts/repair cost (in some regions): Especially if you buy a high-mileage model and need to replace tensioner or deal with leaks.
- Rarer engine option: In some markets you might find fewer specialist mechanics or less used-parts availability compared to more common engines.
Quick Comparison Table
| Feature | Summary |
| Power/Performance | Strong and smooth six-cylinder feel |
| Longevity | Good potential with proper care |
| Maintenance Demand | Moderate – more than small four-cylinders but manageable |
| Fuel Economy | Below average compared with modern downsized units |
| Suitability | Great for drivers who want more than just economy |
If you drive a mix of city + highway, have higher mileage expectations or sometimes carry load/tow, and you appreciate a smoother drive, the Subaru 3.6 is a smart choice. If you’re purely after low running cost and minimal maintenance, you might lean to a more efficient four-cylinder.
Buying a Used Subaru with the 3.6 Engine: What to Check
When evaluating a used vehicle that has the 3.6-litre engine, pay special attention to these checkpoints:
- Service history – Look for consistent oil changes (synthetic), coolant flushes, and records of any belt/tensioner work.
- Oil level and consumption – Inspect under the car for oil leaks; ask when the last oil top-up was needed.
- Accessory belt system – Listen for belt noise, inspect for tensioner or pulley wear; ask if the belt/tensioner kit was ever changed.
- Cooling system condition – Check radiator, hoses, coolant condition; ask if head-gasket or coolant leak issues were ever present.
- General condition and mileage – Higher-mileage cars need extra scrutiny; parts wear increases with age.
- Test drive – Listen for rattling on startup, check for smooth power delivery, monitor engine temperature behaviour and any strange smells/smoke.
- Compression or leak-down test (if possible) – For high-mileage examples it may be worth verifying engine health.
Doing your homework here will increase your chances of getting a used vehicle with a 3.6-litre engine that continues to serve reliably for many more years.
Subaru 3.6 Engine Problems
The Subaru 3.6 engine is reliable but can develop oil leaks, use more oil over time, or have timing chain tensioner wear. Regular maintenance and early checks prevent most issues, keeping it running smoothly for years.
Subaru 3.6 Engine Horsepower
The Subaru 3.6-liter EZ36 engine produces around 256 horsepower and 247 lb-ft of torque. It delivers smooth power, strong acceleration, and excellent highway performance—perfect for drivers who want extra strength compared to the smaller 2.5-liter engine.
Subaru 2.5 Vs 3.6 Reliability
Both Subaru 2.5 and 3.6 engines are dependable when maintained properly. The 2.5 offers better fuel economy, while the 3.6 provides more power and smoother driving. The 3.6’s reliability is solid but needs slightly more attention and care.
Subaru 3.6r Engine Specs
The Subaru 3.6R engine is a 3.6-liter flat-six producing 256 hp and 247 lb-ft of torque. It features a DOHC design, timing chain, and all-aluminum build, offering balanced performance, durability, and a refined driving experience.
Subaru 3.6 Engine Timing Chain
The Subaru 3.6 engine uses a durable timing chain instead of a belt, meaning it usually lasts the engine’s lifetime. However, chain tensioners may wear over time, so regular oil changes help keep it in good condition.
Subaru 3.6 Longevity
With proper care, the Subaru 3.6 engine can easily last 200,000 miles or more. Using good oil, maintaining coolant levels, and fixing small leaks early help this strong engine stay dependable for many years.
FAQs
Which Subaru to stay away from?
Avoid older Subaru models with known head gasket issues, especially early 2000s Outback, Legacy, and Forester models.
How long do Subaru 3.6 engines last?
The Subaru 3.6 engine can last over 200,000 miles with regular oil changes and proper maintenance.
Which is the most reliable Subaru engine?
The Subaru 2.5-liter and 3.6-liter engines are both reliable, but the newer 2.5 Boxer engine performs most consistently.
Does the Subaru 3.6 have a timing belt or chain?
The Subaru 3.6 uses a strong timing chain that normally lasts the entire life of the engine.
What years did Subaru have a bad engine?
Subaru engines from 1999 to 2011 had some head gasket issues, especially the 2.5-liter models.
Which Subarus have transmission problems?
Some 2010–2015 Subaru Outback and Forester models had CVT transmission issues if not properly serviced or maintained.
What is the biggest problem with Subaru engines?
The most common Subaru engine issue is oil leaks and head gasket failure, mainly in older 2.5-liter versions.
What is the best year of Subaru to buy used?
Models from 2015 onward are best, offering improved engines, better reliability, and modern safety features.
Who makes Subaru engines?
Subaru builds its own engines in Japan, designed by Subaru Corporation, known for the unique flat-four and flat-six designs.
What year to stay away from a Subaru Outback?
Avoid 2013 and 2014 Subaru Outback models, as they reported more engine and transmission complaints than other years.
Conclusion
The Subaru 3.6 (EZ36) engine stands out as one of Subaru’s most well-balanced powertrains. It combines smooth performance, dependable reliability, and impressive longevity when properly maintained. While it may use more fuel and require slightly higher maintenance costs than smaller engines, it rewards drivers with strength, refinement, and confidence on every trip. For those who value power, smoothness, and long-term durability over fuel savings, the Subaru 3.6 is an excellent choice. Just stay proactive with maintenance, and this flat-six engine can easily deliver well beyond 200,000 miles of dependable service—proving that Subaru’s reputation for reliability is well deserved.