Why Does My Subaru Use Oil?
Why Does My Subaru Use Oil?
For this article I am focusing on oil consumption and not external leaks from the engine, meaning if you check your oil, find it low, it’s not due for an oil change and there are no major visible leaks found with your engine, than this article applies.
If you’re a good car owner you DO periodically check your oil, I suggest every other tank of fuel, but it’s actually suggested by Subaru to do so every tank of fuel.
Why is this important? Over time the internal components of your engine such as the piston oil control rings, valve stem seals, valve guides and cylinder walls can all wear to the point where more oil is actually introduced into the combustion chamber than originally designed. This is a completely normal thing to happen in an internal combustion engine, and as long as the engine isn’t repeatedly ran low or worse out of oil, it won’t really affect the performance of the vehicle. As the engine ages it will reach a point where the piston oil control rings can no longer expand enough to slow the consumption of oil, the engine wears a little, every day you use it. Just like the more you walk in your shoes the quicker the bottoms wear out until one day your foot is wet, one day you will check your oil and it will be low where it hadn’t been before, this is the critical point in used vehicle ownership where staying on top of your maintenance aspects will avoid costly repairs, and not will mean a new engine. Some engines won’t use a drop of oil until the 2500 mile mark and then use a quart in a few hundred miles; this is mostly because of the dilution affect of the oil in the crankcase which I will address in a bit.
The key here is to know your car, and know the point at which it may use a little oil and stay on top of it! If you don’t check your oil how will you know if it’s low? Until the current era Outback limited models there has never been an oil level sensor on a Subaru. Prior to that Subaru used a low oil pressure light, but typically no oil pressure means the damage has in fact been done.
When I worked at the dealer we dealt with new Subaru vehicles that used some oil from day one, and unless it was more than a quart every 1000 miles there were never any warranty repairs authorized. As the internal combustion engine doesn’t achieve 100% combustion as its not 100% sealed it can never not use some oil as part of the combustion process.
Factors that can increase oil consumption are engines that don’t always reach operating temperature, vehicles that have “slow” front air fuel sensors or anything else affecting fuel trim allowing the car to have an excessively rich fuel mixture or problems with the 2 different crankcase ventilation systems. The flash point of your motor oil is one major factor in consumption the more diluted the oil is with unburned fuel the lower the flash point becomes, the easier it is for oil in the combustion chamber to be burned and head out the exhaust with the rest of the byproducts of combustion. What is supposed to happen is the un burnt fuel is designed to re enter the intake manifold and be part of the combustion process, but in order for that to happen the proper temperature must occur for oil vapor to separate from oil liquid. During the winter, stop and go driving and during short trips to the store this just doesn’t happen.
The key here is to be proactive and the more modern cars become the more detached we become of the simple everyday basic aspects of a car, the need to check the oil, the tires, the fluids and the bulbs will never really go away and while systems may be added to cars they are done with a price. An example of this is the low tire pressure monitoring system that adds about $500.00 to each new car now but was closer to $1000.00 just a few years ago.
You can have an engine that uses a quart of oil every 1000 miles and run like that for 300,000 miles as long as you don’t let it run too low repeatedly, or worse out of oil just once. Understanding your car is the only way to avoid costly repairs and life without your Subaru.
Pictured below is a piston from a 2.5l Subaru engine, the lower set of rings are the oil control rings and they are collapsed causing excessive oil consumption.
Subaru Piston and rings
Subaru Piston and rings
Thanks for reading, and check your oil!
Justin
Gospel!!
Very insightful article. Well said.
Thanks for your article Justin. Love your work!
My situation:
I have 2002 Outback 2.5l. roughly 140,000 miles. Head gasket was going and I found a guy who works on these subaru’s all the time do the repair. He replaced the head gasket by the removing the engine method, replacing all the seals and gaskets and reinstalling the engine at the same time. He also mentioned that the person who’d replaced my timing belt earlier had not replaced the components and that they would need to be replaced. He mentioned that he would only charge me the “cost of the parts” for the timing components – $400. All told he replaced the head gasket and timing components for $1900.
Engine ran fine for 90 miles. then the check engine light came on and I brought it back. It was the P0420 code dealing with Oxygen and he suggested that I probably needed a new Oxygen sensor or possibly a new cat.
code came and went for about 2000 miles and I started noticing the idle running low (possibly related to this Engine code I thought). then at about 2800 miles I started smelling weird engine exhaust (Very sweet and sickly). almost immediately I started hearing a clicking sound from the engine that appeared at > 2000 rpms . the next day driving it got louder and the engine just stopped running on the freeway.
I had it towed to the nearest station (not the guy who did the headgasket) and he said the engine was dry of oil and put in at least a quart.
I towed it back to the head gasket guy and he says it was a pin connected to the piston giving way and blowing the engine completely. He had given me a warranty on his work to 24000 and 12 months, but is suggesting that this wasn’t due to his work at all – since timing is still intact. He also said there was 3.25-3.5 of oil in the engine.
Two questions you can help me with for which I’d be eternally grateful – And obviously – I should have checked the oil more frequently than 2800 miles
1. assuming he’s telling the truth and there was only 3.25 in there (so actually I was running the engine at 2.25-2.5 or less)…what kind of damage would that do to the car?
2. Does any part of this story suggest that I should be asking for a warrantied engine?
3. Assuming I get the engine replaced – what should I be concerned with going forward in choosing an engine New vs rebuilt or used?
Thanks so much for you time.
John Sandahl
Hello John,
Your most likely not going to like what I have to say but it is your and your responsibility alone to maintain the proper oil, coolant and every other fluid level in your vehicle. The days of the “full service” gas station have long since been gone, but the need to check the engines oil level every time you refuel your car remains, its just now YOUR job as the market place decided the American consumer did not want to pay for a gas station attendant to check the car over.
I will tell you that you can go through life and never check your cars oil and most times you may actually never have a problem but every once and a while your engine will be low and when it is it must be corrected asap or damage will occur.
“1. assuming he’s telling the truth and there was only 3.25 in there (so actually I was running the engine at 2.25-2.5 or less)…what kind of damage would that do to the car?”
Not sure where these numbers are coming from ? Your Subaru 2.5l holds 4.3 to 4.5 Quarts of oil if none registered on the dipstick, it would have been approximately 2 quarts low on oil. 2 quarts works out to about 45% of the lubrication gone as well as 27% of the engines cooling system gone now as well.
So the engine runs hotter at a time when you have removed 45% of its ability to cool with lubrication and 27% of its ability to cool with fluid. The result is almost always going to be a damaged engine. It really works the same way a lawn mower does, if you run the lawn mower out of oil you do get out of mowing the lawn that day.
I suggest you check the oil on any car you own every 500 miles even if its new!! My 2012 Outback was delivered 1/2 a quart low on oil how would I have ever known if I didn’t check it?
The shop is correct in telling you its not a warranty concern, they have no control over what you do once the car leaves the shop, a head gasket failure and subsequent repair can sometimes create an oil consumption issue, but the fact that it uses oil wouldn’t have been a concern if the oil level was monitored and corrected.
If your cylinder heads are ok, then I would suggest a Reman Subaru Short block, if your heads are damaged I would suggest a used engine, that engine then resealed and after its installed the oil level checked every 500 miles.
I know you spent a lot of money repairing the car, if this happened to one of our customers we would offer to do the repair at a discount to try and help out, I would hope that the shop in question would offer the same.
I know it hurts the wallet and I do sympathize and I am sorry I cant offer more than the truth.
Justin
Great article. Do you recommend checking the oil on a subaru, when it is cold or after it has warmed up?
In my experience if I check the oil when the car is cold (I live in Colorado) after the car has sat overnight the dipstick reads low. However, if I check after driving the car has warmed up – the level reads somewhere below the low and full level. In general, it seems that the subaru dipstick is difficult to read.
Thanks!
Actually either way is fine as long as you know it expands when hot so dont be alarmed if it seems a little over filled. The Dipstick has a tendency to scrape the tube on the way out affecting the oil level readings at times.
Thanks
Justin
Hi Justin..
I’ve spoken to you before.. but this oil issue has me “up at night” ! I bought a used 2000 Outback 87K miles, that had just received the new head gaskets, waterpump, serpentine belt, valve cover gaskets etc.. The car runs like a dream.. I also replaced both front axles, and the converter… so most everything has been done to this vehicle to insure a good long life… The oil thing is weird to me.. using 5W30 here in the NC mountains.. I can never seem to get a good reading on the oil.. NO VISIBLE LEAKS, or drips.. But the car seems to be going through oil.. Took it on 600 mile trip to Florida (average 60-70 MPH) and checked the oil about half way through the trip while fueling, the reading seemed good. No sign of burning oil, no smoke or any external symptoms.. and when I arrived in Florida.. checked the oil when the engine was cold, again all is well.. My wife drove another 3 hours south and back and at that point the car was about 1/2 quart low…just below the F line on the stick.. She began the return trip to NC and about half way back checked the oil and the stick was “dry”… added 1 quart and then the stick read “F”.. Upon arrival at the house, I checked it again in the morning and the stick was reading super low.. I added another quart… Then took it to an oil change place had them drain it and count the quantity of oil coming out.. it was 3.5 quarts.. Which means that I had a quart and a half in the engine… Is that enough oil to safely run an engine on? Is it possible that my engine was damaged by heat BEFORE the head gasket job and I have internal damage? Would there be external symptoms if that were the case? Valve stem seals, rings? Are their symptoms to observe if those two things are in need of repair?
I’ve been told that valve stem seal replacement is about $1500 or so.. and if it is rings… to just get a new engine… because the ring job is more expensive than the car is worth… What do you say Justin.. any suggestions?
Thanks,
Bald Head
Hello Bald Head?
Based on the amount of oil you are going through its most likely worn oil control rings, if the car had overheated at all it will cause this to occur very quickly in some cases.
It means that you can either continue to add oil @ $whatever you pay a quart for the life of the car and as long as you continue to do so it will most likely run as is for very long time, or you can pay to have the short block replaced along with the heads rebuilt, yes the bill may come in higher than the perceived value of the car, but the 2 have nothing to do with each other.
Typically worn valve stem seals or guides will cause blue smoke on start ups after it has sat for a bit. That is one symptom you can look for, but even if you thought it was stem seals, I would suggest at least one piston comes out for inspection and clearance measurements during the valve stem seal replacement process to be safe.
Hope that helps
Justin
Your Independent Subaru Expert
Justin, thanks! about the following comment from you: “or you can pay to have the short block replaced along with the heads rebuilt, yes the bill may come in higher than the perceived value of the car, but the 2 have nothing to do with each other.” Does a replaced “short block”.. well, I’m not sure what that actually is or entails or costs… But would a new short block contain all the new valve stem, piston ring stuff you are talking about above? How much for something like this?
Bald Head
The short block is an engine block fitted with pistons rings crankshaft and bearings.
The cylinder heads would be removed form your Engine, rebuilt with new Valve stem seals, re worked valve guides and a re ground valves and seats.
I just put up a video that shows me in front of half of a cylinder block holding up a piston and showing rings if you need a visual here
http://www.youtube.com/watch?v=MZ8tT28MQYQ&list=UUe0tSf4w8giEP5n9kGhVAjA&index=1&feature=plcp
I have shot some footage showing a short and long block as well as Cylinder Heads but it will be a bit before I have done the editing and post it to you tube.
I don’t know how much a shop near you will charge, kind of like a house is more expensive in Southern California than Detroit.
If you want a shoot from the hip Number $3500.00 to $5000.00.
Hope that helps
Justin
Your Independent Subaru Expert
Also Justin, another question about the oil… in an engine with 88000 miles, like mine… When I change the oil how long would it generally take for that oil to start getting darker in color when I wipe the stick on a paper towel?
Justin!! It happened again today! I went out early in the morning to check the oil (55 degrees).. Just had the oil changed 1000 miles ago.. Check it this morning and the stick is DRY.. absolutely DRY! I checked it 3 times in disbelief.. Then went to the shop around the corner and put in a quart and a half.. and it was FULL on the stick… I’m going friggin crazy here with this car… What the heck? How can it be DRY.. and then add a quart and a half and it is FULL?
Bald Head
You have an oil consumption issue, and the Dipstick may be scraping on the tube while you remove it to check the oil level causing inconsistent readings.
Justin
I bought a subaru impreza 2.5i in 2010. right now it has 54K miles, but after driving it away from the lot with 30K, i checked the oil and it was about a quart low. i filled it up and just figured that the dealership didnt top everything off before i bought it. since then ive been religious about getting oil changes every 3-4K miles for the life of the car. the past two times ive taken it in, the check engine light and the cruise control lights have come on. both times, the dipstick was dry and they accused me of not checking oil as much as i should. the P0028 solenoid codes came up. but they cleared it, did the oil change and it never came back. i may have let it slip a bit, but had been checking every 1000K and adding a quart every 2500 or so or when i felt it was thirsty. so, while still under warrenty i got an oil consumption test at the dealership,just to try and rule anything out, and the results came back that i was 2.5 quarts low after 2154 miles driven. he said that normal oil consumption for subaru’s is 1 qt every 1200 miles. mine shows a bit more than that, however they said that they would “email the area rep and let him know what is goin on. will contact customer when we have more information.” they never did, and my car is not under warrenty anymore.
In my experience with subaru’s, ive always had to add oil, and while trying to sell the car right now for other reasons, its embarassing to show the maintenence records and oil consumption test, already having several people walk away from the deal due to fear of a head gasket issue or that my car is a lemon. I feel the car is immaculate and just that it burns oil and it is what it is. what can i rebuttle these potential buyers with when they get scared about oil consumption? thanks,
Its unfortunate to have to point this out, but you fell into the system and if you have repair orders to prove you and an oil consumption issue like that pre warranty expiration you have a case to make with SOA, but because you bought the car used, there is a good chance who ever had it before you was on the every year oil change plan. Subaru doesn’t have to do anything if thats the case and also if its documented you let the car run low on oil there is also typically no warranty coverage either, its one thing to use oil, another to let it run low on oil
You needed to follow up with Subaru on this if you have the afore mentioned documentation.
If not, thats a tough one to try and help with, many in our society dont want to be bothered with checking the oil so they dont, if you tell them they have to, they my not buy the car, but if your not honest that could be worse if the next buyer ran it out of oil right after they ought it form you.
If it was less than 1 quart every 1000k I would say you just need to find the right reasonable minded buyer but yours is right at that point where its tough to really say thats an ok amount of oil consumption.
I know you are looking for something different than what I have tried to point out, but all I have for you is the truth.
Hope that helps
Justin
Hi Justin,
I bought my 2006 manual Subaru Forester X at 52,700 miles in November 2011. It came with a 152-point check and a 60,000 mile warranty. I had the oil changed the day after I bought it. At about 54,700 miles, we noticed it needed a quart and 1/2 of oil. I mentioned it to the dealer when I returned for a mirror replacement. The service technician said the independent repair shop, where the oil was changed, probably did not realize how much oil the car required, and they didn’t use enough. OK, so I asked him to change the oil; mileage at that point was 56,500. At 58,500, it was a quart low again.
So, I’m at the dealer today, and the service technician said it’s typical for a Subaru to lose a quart of oil every 1,000 miles. She suggested an oil consumption test. I suggested that maybe it’s burning oil, or it may need a valve-job, or some other repair. Rather than leave today without an answer, at 59,991 miles, I asked to have the spark plugs replaced, at my cost of $235, so we could see if there’s oil where it should not be.
If it is true that Subaru Foresters require a quart of oil be added every 1,000 miles, I think that should be disclosed before the customer makes a purchase. I have essentially purchased a car that requires me to check the oil daily before I drive it – and to keep my car stocked with plenty of oil when I take longer drives so I do not blow up the engine or find myself stranded. My previous Subaru Forester XS was a 2003, and it never used oil between oil changes (not once). When it finally did begin to lose oil, the same independent repair shop diagnosed it as needing a valve job at approximately 140,000 miles. I loved that car, yet I do not feel safe in my new Subaru. Is this true that my newer car really can use a quart of oil every 1,000 miles? Or is it more likely that it’s burning oil, or needs a valve job? Since it’s still under warranty, I want to be sure of my options. Thank you! Ann
Have you ever experimented with using something other than 5w30 motor oil to address oil consuption? I have a 98 Outback with around 180k and tried 10w30 castrol high mileage but didn’t really seem to slow it down. What about synthetic, from my experience it seems like oil comsuption is worse with synthetic? I would love to hear what you think.
Thanks
Of course
We have used 10w40 Rotella oil in the 2.0l WRX to help with consumption, 10w30 in the DOHC 2.5 from 1995 to 1999 to help. Tried several different types of oil, grades and weights. If an engine is to the point where its worn and that’s the reason for consumption changing the oil type may not help that much, typically going to a 10w30 over a 5w30 works best when dilution of the oil is causing it to burn at a lower temp.
Justin