what changes were made from 2005 to 2008 subaru engines

Subaru 2.5 Engine: Ability and Performance

Available in multiple configurations and versions, Subaru's 2.5L four-cylinder 'boxer' engine has been a mainstay in the brand's lineup for many years. We review its best aspects.

Of the main Japanese automobile companies, Subaru lone has a reputation for existence a bit quirky. Standard all-wheel drive on most of their cars, unique styling, and a boxer engine aid to separate them from the Toyotas of the world.

When it comes to these unique boxer engines, the heavyweight of the grouping is the 2.5-liter four-cylinder. Available in a bulk of the lineup, the "EJ" and newer "FB" have been under the hood of Subarus for a combined 32 years.

Permit's accept a expect at what the keys to success have been for this unorthodox engine blueprint.

Subaru'due south 2.5L EJ Engine: Why Begin with a Boxer?

We start with the basics: All EJ-series engines share a 16-valve, apartment-four horizontal configuration with i.5- to two.v-liter displacements. But why a boxer to begin with?

Karl Benz (yep, of Mercedes-Benz fame) patented the flat-four engine in 1896, and Subaru introduced it in their lineup in 1971.

Motor Trend explains, "the engine was configured to exist inline with the transmission, and it had a lower center of gravity to help minimize trunk whorl in comparison to inline-four and V-blazon engines, which have a higher center of gravity and are prone to side-to-side vibration."

The design was also lighter and compact, which is important for a young car visitor that was trying to become its anxiety on the footing.

EJ Engines: Naturally Aspirated or Turbocharged

As you lot'd look from an engine that has a xxx-yr history, the EJ could exist had in a diversity of configurations. There is a less circuitous Single Overhead Cam (SOHC) or more efficient and powerful Dual Overhead Cam (DOHC) blueprint.

The DOHC engines are more difficult to service when information technology's time for a spark plug change. So, those engines get platinum-tipped plugs, which extends service intervals to 80,000 miles. You can have your EJ in naturally aspirated or turbocharged form.

All DOHC and 1998 or newer SOHC EJ engines are interference engines, so if the timing belt fails, the valves will likely be damaged. Information technology's recommended to supplant the timing belt every threescore,000 miles to forestall this from happening.

We'll focus on the 2.5-liter engine specifically, which was introduced in the Legacy two.5GT and Outback in 1996. Turbocharging was introduced on the 2005 Legacy and the 2005 revision of the WRX.

Car and Driver noted the difference from the 2.0-liter version in a 2006 WRX. "The newfound power and torque are bachelor at lower rpm, eliminating much of the lifeless feel the WRX had earlier the turbo came bursting into the room around 4,000 rpm."

The EJ25 volition soon be discontinued, with the current WRX STI beingness the terminal model to receive information technology.

EJ25 Engine Problems & Known Issues

Subaru has an excellent reputation for reliability, but there are always bug to be aware of, and the EJ is no dissimilar. Some issues experienced with the EJ engine include a faulty fuel pump that could atomic number 82 to engine stalling, and an engine computer that has the potential to proceed powering the ignition coil even after the motor'due south shut off.

FB25 Engine: Lighter Equals More EfficiencyThe FB25 was introduced in 2011 with the Forester, and though the deportation of both the EJ25 and the FB25 round to 2.5 liters, the FB is slightly larger, at two,498 ci versus 2,457. At that place are once again not-turbo and turbo versions.

Subaru says the primary motivation for the new engine was improved efficiency, and they claim a 28% reduction in friction losses, with the biggest contributors being lighter pistons and connecting rods.

All of this adds upwardly to merely i boosted mpg of range, only that'southward actually a 5% increment, and it'southward deceiving because the FB engine was initially paired with older transmission designs.

With standard all-bicycle drive, Subaru'due south vehicle offerings volition often have less range when compared to a front-bicycle-drive competitor.

This new engine is also chain-driven (as opposed to the EJ's chugalug), which is a more robust setup that allows for a new block design with fewer emissions. It also has variable-valve timing to ameliorate power and efficiency.

"Performing these same upgrades to the EJ would take resulted in a much heavier engine," reports Automobile and Commuter.

Jalopnik loved the boxer/AWD combination. "To Subaru's credit, the Boxer/AWD formula remains bright," they said. "While carmakers are throwing all the technology they tin at their all-cycle-drive systems to make sure young families don't fall off a cliff in their crossover, none of them volition ever match the low center of gravity of a horizontally opposed engine."

FB25 Engine Problems & Known Problems

Some of the FB series engines swallow oil, with owners needing to summit off the oil level every few thousand miles. YouTuber mechanic Mr Subaru 1387 tells us that, "this raises some business when it comes to longevity," and that "as they habiliment, oil consumption will rise." This could lead to deposits on your pistons, spark plugs, and oxygen sensors. Non helping matters much, is the oil spec for this engine — a very low-cal 0W-twenty.

MDH Motors took a failed FB25 autonomously to find, "This engine burned oil and so badly that information technology damaged the catalytic converter and completely burned up the exhaust valves." To solve this, Subaru has issued a Technical Service Bulletin that replaces toe piston rings after inspection, if they decide the engine is consuming too much oil.

There was also a recall for engine valves that can fail, according to Consumer Reports in 2019. "Subaru is recalling sure Crosstrek, Forester, and Ascent SUVs and Impreza hatchbacks and sedans because they can suddenly lose power while driving, which could cause a crash," says Consumer Reports. "A faulty role in the engine could allow oil to enter places it shouldn't. Pieces of the part could also separate and damage other engine components, which could cause the engine to of a sudden lose ability."

Differences Between the EJ and FB Engines

The EJ was phased out in the late 2010s considering of limitations in its design, such as port fuel injection verses newer direct injection in the FB engine.

Over at EngineBuilder, Justin Anning of Nemesis Performance explains: "It is a completely unlike design than the EJ, although it still remains an opposing 4-cylinder. It has direct injection technology, a mechanical fuel pump, and asymmetrical connecting rods."

Engine Works states: "In comparison with the EJ25, the FB25 is more responsive at depression speeds. Having an identical output, information technology achieves lower rpm and higher torque at lower rpm. Moreover, it consumes less fuel."

Should You lot Purchase a Used Subaru with Either the FB25 or EJ25 Engine?

We'll employ the Forrester every bit our example, as information technology's Subaru's most popular model.

Autotrader gives an of import tip, "Those seeking to spend a chip more than should jump to the fifth-generation Forester, preferably a 2016 or newer, as these models don't suffer the oil consumption bug that plagued some 2014 and 2015 models."

Subaru offers certified vehicles that are subjected to a 152-betoken inspection and a seven-twelvemonth/100,000-mile warranty on the powertrain, so that should offer some peace of listen in regards to the longevity of your Subaru engine.

A Subaru offers a lot of advantages over its competition, and with an overall dependable reputation and the condom of standard all-cycle drive and, you'll be able to bask many trouble-gratis miles with your Subaru ii.v-liter engine, regardless of the model you choose.

Photos: Subaru

Oft Asked Questions

Apr 1, 2022

Is the Subaru Outback two.5 underpowered?

The Subaru Outback with the ii.5L 4 cylinder engine comes standard with 182 horsepower and 176 pound-feet of torque, which is less than a lot of the other competition on the market. The outback also has a curb weight of three,637 to three,937 pounds depending on the options that are selected from the manufacturing plant.

This gives the Outback a cipher to threescore time of nine.four seconds which is slower than a lot of the other vehicles in its class. The Outback is non designed to be a sporty and fast vehicle though, it is fabricated to exist reliable and handle on and light off-route terrain well with its all-wheel-drive arrangement.

Determining if the Outback two.5L is underpowered comes down to a lot of personal preference. If you like a sportier vehicle then the Outback will experience a bit slow to you. If you are not out to get the best nada to sixty time then the Outback may be fine for y'all. The 2.5L motor makes enough power to let the Subaru travel at highway speeds with no problems.

Is the Subaru 2.5 a good engine?

The Subaru ii.5L engine has a mixed reputation. A lot of the earlier versions of this engine that were produced from the late 1990s through near 2007 take been known to have caput gasket failures on them that can destroy the engine. In recent years however the 2.5L motor has been revised and has become significantly more reliable.

The 2.5L motor no longer has the same failures that plagued the earlier generations, merely they are however known to have oil consumption issues. These engines will typically burn and employ more than oil than nearly other iv-cylinder engines, so it is important to routinely bank check your oil level to make sure that it is properly filled.

The 2.5L motor at present is known to be a fine motor and as long equally you take care of information technology you should have no problem getting hundreds of thousands of miles out of it. In recent years Subarus accept increased in popularity since their overall quality has improved.

How long do Subaru 2.5 engines last?

A modern Subaru two.5L engine should accept no problem lasting over 200,000 miles as long as you accept care of it. There are plenty of 2.5L engines that have lasted over 300,000 miles equally well when owners have washed the regular maintenance on them such as oil changes, spark plug changes, and coolant changes.

As long as you get your scheduled maintenance services done and do not push your engine to redline all of the time yous should have no problem getting a modern Subaru engine to last. There have been issues in the past with the ii.5L naturally-aspirated engine from Subaru, merely most of those problems have been fixed over the years through different revisions.

Subaru is at present known for making reliable vehicles that are well built, and a good value for what they are. The two.5L motor is used across many different Subaru models and all of them accept plenty of reports from loftier-mileage owners.

Possessor Reviews

Craig B. on December twenty, 2021

Weak engine, Incredibly expensive transmission

We accept a 2014 outback with 152,000 miles. Oil consumption is increasing, peculiarly at throughway speeds. The cvt manual grinds if i of the front end wheels slips. At 50,000 miles 1 of the mechanics at Premier Subaru in Santa Iron slid the motorcar into a curb pulling it out of the dealership, wrecking the right front rim , wheel begetting, and lower control arm. I question now if that was the start of the grinding problem we now take. Based on the potential cost of these 2 problems(over 10K!), I volition non buy another Subaru. Their repair costs, specially on their transmissions, are ridiculous! In the by I have had used Subarus and ran them over 200,000 miles with no problem. This motorcar probably won't make information technology. I considered some other Subaru with a three.half-dozen motor, only they discontinued the 3.6. I have NO FAITH in their 4 cylinder engines, especially the turbocharged ones. Every few years they come upwards with an improved 4 cyl engine with new bug. Their quality is slipping while their prices climb.

Alex G on Baronial i, 2021

2018 Subaru WRX sti; your next car for the residual of your life.

The Subaru sti is by far my favorite vehicle that I have always owned. It delivers tons of power with it is 305 horsepower turbocharged motor and infrequent handling with information technology is all cycle drive. I was pleasantly surprised by the manner selector characteristic that the newer WRX/sti models take. You can choose between 'intelligent, sport and sport precipitous' modes. Intelligent lowers the ability output of the engine and boosts fuel economy while the sport and sport precipitous increase power at the price of fuel efficiency. This gives you the ability to salve some gas while driving in cities then open up it up on the highways!

J.Grenzer on January 24, 2022

2018 Outback 2.5 50 engine

Squeamish car, but terribly expensive maintenance. Paid $707.00 for transmission fluid modify and spark plug replacement at a Subaru owned store. Should mention that I supplied the spark plugs, since the NKG'south were $47.00 cheaper at Candian Tire vs. The dealer price. The service took exactly xc minutes. I know the service is charged on a apartment rate basis, only the accuse is just prohibitive and needs to exist reviewed by Subaru.

Sam M on July 29, 2021

2020 sti review, after a year of ownership.

It has 310 horsepower, which is plenty to make it feel peppy, although in my opinion information technology could employ maybe 80 more than horsepower. Only in reality, that is not what this auto is fabricated for, information technology is made for sliding on dirt and cutting upwardly the back roads. With it is drive mode selector, and centre unequal controller, this car can become from feeling like a tight sports car, to a rally gear up beast.

Steven R on August 1, 2021

2010 Subaru WRX lots of fun.

Performance is nifty for a quick thrill with this turbo. For a daily driver this Subaru tin can take your regular commute into another fun ride. Been reliably on trips around the state (CA). Able to get into identify with its AWD. Had very petty problems with but normal clothing and tear on the vehicle.

Dana S on August 8, 2021

2015 Subaru WRX not worth the engine troubles.

The engine blocks are known to fail. My short cake had to be replaced after 50k miles. The motorcar has not been the aforementioned since. In that location is constant engine knock sounds which make me fearful of driving the car. I am afraid the engine will blow once again and I cannot afford to prepare information technology again.

Peter W on Baronial 10, 2021

My Subaru outback 2017 the vehicle I would by any given 24-hour interval.

I like it for reliability. This car is congenital to last and the performance is fantastic. The fuel consumption on my 2.v is actually good for that size engine too. I can get up to 35 miles per gallon on the highway and 27 miles per gallon town running.

Jim C on July 28, 2021

The cute and sporty 2019 Subaru outback 2.5 touring.

My car has the standard four cyl engine, but even without the available turbocharger, information technology gives me very acceptable operation. The CVT transmission works great, the gas mileage is an average of 26.five. I am totally satisfied with the vehicle.

Jeremy B on July 31, 2021

The 2015 Subaru WRX Premium quad tips are a really nice touch, and they audio good as well.

And so far the machine has been slap-up. Boxer engine has great reliability, and I would well-nigh definitely recommend it every bit a car selection. I have not had any bug with it, and I hope to run across the car perform for years to come.

Bradley K on July 27, 2021

Very fast, heavy clutch...2019 Subaru WRX STI

Everything is spectacular and I couldn't have asked for annihilation improve. It is a very fast machine simply based off of the stock model just is like shooting fish in a barrel to add together modes to make its faster and louder.

Brent B on August 11, 2021

My 2019 Subaru WRX sti, my favorite car I take owned.

The performance is fun and you lot can really brand it your ain car. The only downside would be poor gas mileage and depending on where y'all live, high insurance costs.

Elias on July 28, 2021

Turbo issues 2018 Subaru WRX sti-limited

Only complaint I have is my turbo just recently broke. Information technology won't make any boost at all and for the life of me tin can't effigy out why, the auto simply has 20k miles.

Jt on Baronial four, 2021

2019 Subaru Crosstrek express is fantastic.

I think it is the near fun car I take driven. The gas mileage is unbelievable. I drove a 92 mile trip the other 24-hour interval and registered 38.ix mpg at about 70 mph.

Mckenzie L on August 6, 2021

I dear my 2019 Subaru Crosstrek Express.

The only affair I wish, was that the engine had a petty more horsepower. Not for pulling power, but for city driving when y'all need to get up to speed fast.

Joey Yard on July 31, 2021

2015 Subaru WRX Premium. Outdoors sports auto for you lot.

Very fast, with a turbocharged boxer engine, only still is able to use its performance in all conditions considering of its astonishing symmetrical all wheel drive.

Alec J on Baronial 2, 2021

2011 Subaru WRX a versatile vehicle packing ability and reliability.

It handles well and has a very reasonable amount of ability. AWD standard is a huge selling indicate. The turbo iv cylinder engine is great for fuel economy.

Lucy S on Baronial v, 2021

Loving my 2018 Subaru WRX STI Express.

I love this car! It handles corners amazing and is very peppy. Information technology has a sport mode which makes the shifting quicker but the car feels faster.

Cheyenne S on August 5, 2021

2020 Subaru WRX STI's are the all-time! Definitely a great purchase.

Very sporty with a lot of go up in get power. Everything on the car is very durable. Cannot think of any problems that the auto has.

Ryan Southward on Baronial 2, 2021

2018 Subaru WRX sti review.

Cracking automobile. Fun, quick, and then far reliable. Handles amazingly. Fun motorcar to keep as a daily or to use as a weekend track car.

Juan R on July 27, 2021

Reliable. Friendly. Fun. 2015 Subaru WRX Premium

Starting time off, it is a turbocharged engine that produces 260 hp and has plenty of torque and so it is very fun to drive.

Hazie W on August half-dozen, 2021

My 2019 Subaru WRX STI has turbo.

My automobile drives fast fresh off the lot and the cost is inexpensive to maintain information technology if you take expert care of your car.

Santiago Grand on July 29, 2021

2018 Subaru WRX STI Limited. Powerful performance machine.

This functioning machine is powerful and fast. Drives really well in the street too as in the highway.

Sean Y on Baronial 11, 2021

2017 Subaru Outback is super safe.

The car has a scrap noise, and not the best in power (ii.5 liter).

Andre J on August 5, 2021

The 2019 Subaru WRX STI is exactly what I idea information technology would exist and exactly what I wanted.

No issues with my 2019 Subaru WRX sti. Fast fun car.

Jason T on August 2, 2021

2019 Subaru WRX STI is the car I have always wanted.

My 2019 Subaru WRX STI doesn't withal have any issues.

Nick D on July 28, 2021

2019 Subaru WRX STI: Fun route going rally car!

No issues, the functioning of the sti is awesome!

Zaphod P on August 3, 2021

The 2009 Subaru WRX turbo charged engine is peachy.

Information technology has bang-up performance and handling.

Michael D'Ambrosio

Mike D'Ambrosio is an automotive author and photographer whose work has been featured in multiple publications, including Roundel, Jalopnik, Performance BMW Mag, and Speedhunters. As a creative director, he'southward worked with clients like BMW, MINI, and Jaguar Land Rover. He too maintains the automotive photography blog MachinesWithSouls.com.

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Source: https://www.vehiclehistory.com/articles/is-the-subaru-2-5-a-good-engine

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