Subaru is a well-known company among automakers, with a wide range of highly reliable vehicles and engines. But, this doesn’t mean that their engines are perfect, especially in the case of the 2.5-liter boxer engine, which is infamous for its gasket problems.

Subaru engines have experienced recalls in 2018, 2019, and 2020 because of diverse problems, but the Boxer Engine receives specific attention because of its unique design. Let’s take a further look.

Does the Boxer Engine Have a Flawed Design? 

Some car enthusiasts would argue that the main reason why the 2.5-liter engine has so many gasket problems is because of its flawed design. It is also known as a flat engine and is different from the standard engines in modern vehicles.

In boxer engines, the piston is arranged horizontally rather than vertically. But this also means that oil and coolant don’t drain out of the car when it’s resting, leading to further problems. 

But the boxer engine is not all bad, as it is designed to protect drivers from severe injuries in case of a collision. Since it is a shorter engine, it is pushed to the car floor, not the driver’s seat, when there is a collision.

Common Problems

Although the common problem among 2.5-liter boxer engines is gasket failure, you also have to look out for radiator problems caused by leaks and cooling problems, although less likely to happen.

Gasket Failure 

Gasket failure in the boxer engine is caused because the oil and coolant can’t drain out of the car. So, they end up in the gasket, which further leads to gas and liquid leaks in the vehicle. The job of a gasket is to connect irregular surfaces in the engine and is needed for the whole system to work correctly.

If you’re using an older Subaru, your gasket can get worn out quicker than newer engines. Also, fixing gasket problems is highly expensive but essential, as they can significantly reduce the Subaru vehicle’s lifespan.

The good thing is that this problem is hardly present in new Subaru engines, but if you’re buying a used car, you’ll need to check for gasket failure often. You can check by placing a dipstick into the oil, and if it looks white, it has mixed with the coolant. You can then hire a professional to fix the problem as soon as possible.

Radiator Problems

As the oil and coolant leaks don’t drain the vehicle, they sometimes get into the radiator. One of the common radiator problems is coolant corrosion, caused by a lack of coolant flowing into the radiator. A symptom of this particular problem is overheating when driving on hills or highway speeds. 

Dirt and debris can also build up in the engine’s radiator, another common problem in Subaru 2.5 liter engines. This hampers airflow and requires the help of a professional mechanic. 

Coolant and Oil Leaks

Another problem caused by the horizontal design of the boxer engine is coolant and oil leaks. Older engines mostly had coolant leaks on the left-side gasket, which prompted Subaru to add an anti-leak system conditioner to new engines.

But the good thing is that you can easily spot coolant and oil leaks since the engine is close to the ground. Once you identify it, you should quickly fix it to avoid further problems. You can also ask the mechanic to check for leaks in the head gasket whenever you’re changing the oil. 

Is the 2.5 Liter Boxer Engine Reliable?

If you purchase vehicles with the newer engines and not the original, you can enjoy reliability with your Subaru 2.5 liter boxer engine. Many car owners usually hesitate before buying cars with this engine because of the history of faults and recalls. 

When the engine first hit the market, it displeased the customers with constant maintenance problems. But what many people don’t see is that Subaru worked on developing their engine to prevent these issues from 2009 to 2012.

So models made after 2012 significantly increased life expectancy and fewer issues. You can enjoy the same reliability and quality offered by other Subaru models in this engine.

How Long Will The Subaru 2.5 Liter Engine Last?

The lifespan of this boxer engine will depend on how well you maintain it, and if you purchased a used vehicle, maintenance becomes even more critical. Without this, you can’t get a lot of miles out of it. You would only use the Subaru 2.5 liter engine for 90,000 miles in worse cases.

But with proper maintenance, your engine can last for between 250,000 and 300,000 miles. You can take care of your engine through regular battery cleaning, oil change, and coolant replacements. 


In conclusion, you can’t go wrong with the 2.5-liter boxer engine in Subaru models as long as you purchase newer ones, 2012 and older, and take care of it properly. Even if the engine has had problems in its past, this happens to every automaker at least once in their history.

Since Subaru has learned from its mistakes and inculcated changes into the newer engines, you won’t have to worry about these problems as much as before. But, you still need to check the vehicle you’re buying thoroughly, ensure the engine is new or, after 2012, if it’s a used vehicle, and maintain it regularly. 

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Pavlo Prannyk
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