Subaru Oil Consumption Problem & Repair


Genuine Subaru OEM parts only for these engines

The Subaru 2.0L, 2.2L and more common the 2.5L engines are great motors that last forever when maintenance correctly. Most Subaru owners are aware of the common oil leaks that develop as you start to put miles on them. Subaru owners seem to be well aware of the infamous headgasket failure on these engines also. These engines like to leak oil but they’re worth it to fix because they’re just so reliable. If you read the Internet you’ll find multiple articles about Subaru oil consumption problems and read about lawsuits or what not but what you don’t find is why these engines are having such a big problem with oil consumption in the first place. One thing that cannot be corrected which contributes to the high oil consumption rate is the way the engine is designed. The pistons are sliding horizontally about less than 6 inches above the oil pan and any bit of excessive crankcase pressure will cause piston to suck oil as they travel back and fourth right above the oil pan. If you have ever seen these engines torn down with the block split then you would probably understand what I’m explaining better. So, with that being said we know Subaru engines are prone to having oil consumption problems but if everything is working correctly then the engine should not burn the oil up. If you’re wondering why you don’t notice or see it burning and your car will just all the sudden be low on oil that’s because you will not see the oil consumption (oil burning) either. Most all of the burning oil smoke is covered up by the catalytic converters. Extended oil changed intervals are another huge contributor to this. The manufacturers have stretched out there oil change intervals to over 7,000 miles and conventional oil breaks down at 3,000. Then you add the Subaru oil consumption problem on top of the manufacturers recommended extended oil changed intervals where the oil is already broken down after 3K you have a oil consumption problem where you can damaged the engine from running it low. I recommend to all of my customers to check their oil level every 1,000 miles and to change the oil every 3,000 for conventional oil and every 5,000 for synthetic oil.


Pistons removed before cleaned and serviced


Oil drain back holes get plugged, 4 holes on each side of the piston

What causes these already prone for oil consumption Subaru engines to start burning the oil? There are 4 to 5 oil drain back holes in the pistons that plug up not allowing the oil to drain through the oil scraper rings. The rings also get stuck in the piston not scraping the oil off the cylinder correctly. These two things cause the excessive oil consumption. The good news is that the pistons can be serviced without completely rebuilding the engine. Earlier I mentioned the infamous Subaru headgasket failure, we’ll when replacing the headgakets we can remove and service the pistons and piston rings without touching the rod or main bearings (is how the engine is rebuilt anyways). The engine block has piston access holes so just open the access hole, remove the circlip, tap out the wrist pin and then tap the piston out of the block. Now you can either replace the rings if needed or soak the pistons in carburetor cleaner dip for at least 24 hours then the rings should pop right out and don’t forget the clean the piston drain back holes. I have seen this problem develop at 60K, 80K and any engine over 100K always has this problem. Your Subaru 2.5Lwill need the headgaskets replaced sometime in its lifetime so monitor your oil consumption and mention this service.


Pistons removed after cleaned and serviced


Exhaust valves burned from excessive oil blowby

Here at MDH Motors we offer the service and I see a huge improvement in the engine drivability after these repairs. First off, you’ll probably need the exhaust valves re-faced (they get pitted and charred up from the oil burning) the intake valves and seats are usually okay. Second, the piston ring service restores loss compression so the engine will drive better, return the loss of power and get better gas mileage. I’m really impressed at how well theses engines run after this service, it will practically be a new engine for half the cost. Our headgasket repairs usually run from $1600, $1700 to $1800 and if you add the piston ring service while repairing the headgaskets it can be around $2500 or more. Keep in mind that these are just baseline costs and every job is different. Also we are a low overhead repair facility and have a discounted labor rate. Most other repair facilities cannot offer this service at this type of pricing. We specialize on these vehicles so we can do them more efficiently than most so don’t expect this type of pricing at your neighborhood auto repair shop. Also not very many repair facility’s are aware of this service and will just sell a complete new shortblock, which would cost $4000, $4500 to $5000 or more. This is what the Subaru dealerships are doing. They will not remove the pistons just replace the engine for the problem. In my opinion it wastes good engines which require a lot of energy to make so fix what you can to help save our environment instead of just replacing everything. Our automotive industry has became very bad for this, nobody wants to repair things anymore because everything today has to be right now, cannot wait for a rebuild just replace it. If your interested in this service you can contact us to schedule an appointment. Please leave your questions and/or comments below, thanks for reading.

This post was written by: Martin Hand


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Martin Hand

About Martin Hand

ASE Certified L1 Advanced Mastertech. Martin Hand has over 15 years experience in Asian and European Import Auto Repair. Specializing in electrical diagnosis, engine performance, AT/MT transmission repair/rebuild. Martin is also pursuing a degree in Computers Science & Information Systems starting at Portland Community College while he plans to transfer to OIT. Certified in Java application level programming, experienced with other languages such as PHP, Ruby, JavaScript and Swift. Martin has future plans of automotive diagnostic software development.


  • Dale says:

    You can solve a mutitude of these problems by changing your oil at the old tried and true interval of 3000 miles

  • marc lambert says:

    Hi great site, I recently purchased as 2012 Forester with 155 000 k , my mechanic checked it out seemed fine burning 500ml oil 300k no smoke runs fine, would your ring replacement technique be suitable it is a JF motor, my mechanic is wondering how you hone the bore with the block in one piece with rods in, mechanics over here either Subaru dealers new motor, most private mechanics unaware of the problem at all or have heard they still use oil so refuse to fix.

    Do you agree that part of the problem is looser fitting pistons in some new vehicles, I really like the car and my mechanic is devastated I am not happy either, I could live with some oil use has it stayed stable with 5000k oil changes, do you know what is the heaviest oil I can use for now.

    This has been very frustrating these cars are being passed around over here like an STD by dishonest dealers and private sellers that got stuck with them I can not do that, thanks Marc Lambert.

    • Martin Hand Martin Hand says:

      Cylinder wall crosshatch usually never wear so you don’t need to hone it otherwise you would need to split the block, at that point a full rebuild would only make sense. The rings will seat just fine a lot of times we don’t even replace them just clean them up so they’re not stuck in the piston and clear the oil drain back holes as described in the post.

      • marc lambert says:

        Thanks heaps, so at 155 000 k should not need hone in theory, the JF motors are worse that the early and late ones 2011 to 2014 are know as the ugly motor, could it be that they have made the pistons a little looser in the bore, this is supposed to be common in some new motors as they try to get friction down, what is the heaviest oil I can run in it for now while I organise a ring job, I am running 5 40 synthetic at the moment I am in a hot climate.

        You are the first person making sense about these motors, thanks again Marc.

  • […] It may be hard to determine when you already have oil leaks but be aware of the engines oil consumption rate. Some of these engines also have oil consumption problems that can be corrected when replacing the headgaskets. The oil consumption problem is most likely caused from stuck piston rings and plugged oil drain back holes in the lower piston ring groove. Unlike most engines the pistons can easily be removed when the engine is removed and the cylinder heads off. It is not always necessary to remove the engine to replace the cylinder headgaskets but if the engine is removed keep this in mind in-case you have oil consumption problem. If you want to know more about replacing/repairing piston rings read this article here: Subaru Oil Consumption Problem & Repair […]

  • Rom B says:

    What are your thoughts on soaking the 2.5 pistons, with a decarbonizing solvent, in place through the plug holes over night then flush the sump clean and refill with new filter. Might not be good to enter exhaust valves but would that damage anything?

    • Martin Hand Martin Hand says:

      They make solvents you can run before you change the oil + filter to help break free the stuck rings. This really works good as a preventative maintenance but if you already have excessive oil consumption then the only way you going to correct the problem for sure is by removing the pistons and cleaning them that way and/or replace rings if needed.

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