I have a 2010 Subaru with 150000 miles, recently it overheated, I pulled over to check the coolant level and found it was almost empty I filled it up and drove to the dealership where they preformed a smoke test which it failed. The head gasket failed, so they tore it down and found a leaky head gasket and burnt valves. The repairs were made and off I go, after driving about 800 miles the low oil light came on, I pulled over to check the level it was a quart low, I filled it up and started to monitor the oil. It seems to now be using half a quart per tank of fuel about 420 miles, this car never used a drop before this event, I think there is something wrong with the head job, a leaky valve seal or something else. I would appreciate your thoughts, Thanks
When an engine overheats, it can cause the oil control rings the break.
When this happens, oil is able leak past the oil control rings and is burned.
So basically, the damage has been done. So you either live with the oil consumption, or rebuild/replace the engine.
Tester
You can ask Ray at CarTalk what to do but I’m sure his answer is going to be the same as everyone else’s. The mechanic who did your repair did not do the diagnostic that was needed before replacing the head gasket and sending you on your way. Stop fretting over leaky valve seals or any other part of diagnosing the problem. Just set up an appointment with the service manager and ask him to get a more experienced mechanic to rebuild the bottom half of your engine and apply what you already paid to the bill. You’ll come out with a good as new engine good for another 150K miles. These engines are sensitive to being run low on coolant so next go 'round you can be extra careful and get even more than 150K miles.
Thanks I thought this was the problem wend they rebuild the top , that doesn’t explain the rapid increase of oil consumption . I’ll keep you informed of the outcome.
Tester explained to you why the rapid increase of oil consumption.
@Tester has it right. The oil consumption did not increase after the repair, it increased after the damage due to overheating.
Replacing the head gasket $ solved on of the problems but with out a rebuild/replace $$$ you still have another.
you spent 2000 on a top end rebuild. and if the dealer/shop wants 5000 for a new motor will they deduct your 2000 already spent?
I didn’t hear that the dealer agreed to credit the money already spent toward a new motor, or what the actual price would be. However, suppose that your numbers are correct. $3000 can buy a lot of oil, and can replace the exhaust manifold with integrated catalytic converter several times as well.
I would just live with it, and top off the oil as needed unless performance becomes a problem. The car has 150,000 miles now, and most people would expect to get 200,000 miles out of it. I doubt it would be problem to reach that mileage just by adding oil as needed, and maybe having to replace the exhaust manifold once if the cat plugs up, which may not ever happen.
tough call. new heads, gaskets but it burns oil. you could buy a new shortblock and reuse heads and timing belt and waterpump and so on. would shop want to transfer the topend stuff?
or buy a new longblock. that is pricey though
Is that for low oil pressure, or for low oil level? Usually there is a light for low oil pressure, but not for level. If the OP is low, that’s a strong diagnostic clue. Others here can explain it better than I can.
Just a point of interest before the overheating light came on the ac was doing weird things it would cool and then it would blow warm air, I think this was the warning sign I missed, but who new, now I know.
I have owned cars that I would be happy if I only had to add a quart of oil every 800 miles. If you change oil every 5000 miles, you are using 6 quarts between changes. Go for the house brand oil or oil that is on sale that meets or exceeds the specification in your owner’s manual and drive on.
Aren’t the two gaps in the oil control ring assembly simply the ends of the upper and lower ring that surround the wavy part? On my motorcycle and scooter engines the oil “ring” is made of 3 pieces, just like what I see here, and the service manuals always tell me to space the openings about 120 degrees apart. Granted, this piston has seen better days, but I’ve seen them with the oil control completely plugged up with black hard glop.
I’d put Marvel Mystery Oil in the fuel and added to the oil for a few thousand miles. Might free stuck rings, and won’t hurt. Don’t let the oil get too low, or go over about 6,000 miles or 6 months
Did you have low oil pressure, or low oil level, or both?
Overheating an engine can warp or score cylinders, that results in high oil consumption. If new piston rings are installed they will take years to seat in a warped cylinder so oil consumption will still be a problem.
This is the engine from the last car that was driven without coolant until it quit, note the cylinder wall damage.
As far as I know Subaru only added low oil level warning to Gen 3 starting 2015. It’s kind of funny if you think about it, every manufacturer ought to have a low oil level warning since a low oil pressure warning is kind of like saying Game Over. But when does Subaru add low oil level warning? After the supplier sold them bad rings that led to a class action lawsuit which they lost.
Your best bet at this point is just to top the oil off when it gets low. At appx 1000 miles per quart, that isn’t a big oil burner. Some brand new cars today use oil at nearly that rate.
If you want to do something anyway, first thing I’d do check to see if there’s a big puff of black or blue smoke that comes out the exhaust pipe the first start of the day, which would indicate a valve stem seal problem. After that, an oil pressure test and a compression test. That will give you some data to base a decision on what to do next.
Thanks I did notice a puff of blue smoke a few times when I first started the up, I have an appointment tomorrow with the dealership to discuss my options, we’ll see where that goes.
Ask them if they replaced the valve stem seals during the prior work.