Oil problem with Subaru Forester 2007



I took my 2007 Forester to the dealer because the dome light wasn’t going on when I opened the door. While there for that repair under my warranty, they asked me where I had been taking my car for maintenance. I said only to you. They said there was sludge in the engine and that it needed to be cleared out. They said I also needed an oil change (I had had one 5,000 miles before) because I was two quarts low on oil. This all sounds both fishy and scary to me. I said something must be wrong with the car if it loses two quarts of oil in 5,000 miles and that they should find out what was wrong. The dealer said that was normal. No one I know considers that normal. Has anyone else had a similar problem? Any ideas what could be wrong? Does anyone consider losing two quarts of oil in 5,000 miles normal?


2 quarts over 5000 miles is higher consumption.

However you should always check your oil every 3-4 fillups and top as needed.

My guess is the engine was possibly shorted around a 1qt or so and you are seeing normal consumption + that on a 2007.

I would start checking your oil every 2-3 fillups and keep track of added amounts. Othwerwise you are setting yourself for some very expensive car repairs.


Before getting into a discussion of normal oil consumption, somebody has to point out to Bellaluna that her failure to check the engine’s oil level between oil changes constitutes owner negligence.

The object is to never allow the engine’s oil level to fall more than 1 qt below the full mark on the dipstick. Once the first qt of oil is consumed, the rate of oil consumption increases geometrically because the remaining 4 qts of oil have to do the lubricating and cooling work of 5 qts, which they are not able to do properly.

The remaining oil then becomes more contaminated with combustion byproducts and its viscosity begins to break down, thus further increasing the rate of oil consumption. Then, after more oil consumption, the remaining 3 qts of oil becomes extremely stressed, and it breaks down even further. As the oil is consumed, the rate of engine wear also increases–and that is not good.

So, whether the engine was “shorted” on oil at its last oil change or not, the fact remains that the OP is not doing herself or the car’s engine any favors by ignoring the most basic part of car care–opening the hood at least every few weeks and checking the level of all the fluids.

As to what constitutes a normal rate of oil consumption, every car manufacturer with which I am familiar will state that the consumption of 1 qt every 1,000 miles is “within normal limits”. That is not to say that this rate of consumption is desirable, but that it is certainly not unheard-of. Thus, the consumption of 2 qts within 5k miles would be considered “normal”, even if it is not desirable.

Now, we come to the issue of oil change intervals. Whether a 5k regimen for oil changes is acceptable depends very much on how long it took the OP to accumulate those 5k miles. If she accumulated 5k miles in 6 months or less, then changing the oil every 5k is probably okay. However, if it took more than 6 months to accumulate those miles, then the OP is not changing her oil often enough.

If the OP has not been changing her oil often enough over the past 3 years, it is entirely possible that the engine has accumulated sludge and that an engine flush was a good idea. She needs to give us more information on her maintenance schedule in order for anyone to make a valid judgment on that issue.

However, until we get more information, the only thing that appears “scary” (to use the OP’s terminology) is someone who fails to check his/her oil between oil changes. That is one of the best ways to increase the rate of oil consumption, to cause a build-up of oil sludge, and to cause serious engine damage.

Unless the OP wants to continue to court danger for both her engine and her pocketbook, she will get into the habit of checking her oil and other fluids at least once every 2 or 3 weeks.


Actually, what you should do at this point is to ask them to SHOW you the sludge.
I’d like to know how this dealership found sludge in the engine when the car was brought in because the dome light wasn’t working.

I have a very hard time believing that there’s any sludge in the engine.
How many miles are on the car?



An engine can very well sludge up due to 5k miles oil change intervals depending on the driving habits and environ conditins.
An issue to me is how they determined this. Practically, the only way of even making a reasonable guess on this would be if the bottom of the oil filler cap was sludged up.

An even bigger issue is your not raising the hood to inspect the oil level and eventually this is going to come back and bite you; just as it has a number of other posters on this forum. There seems to be a real rash of this over the last year or so.

As to oil consumption a lot depends on mileage, how the car was broken in, any overheating episodes, and one of the biggest ones of all; not changing the oil regularly enough.
Extended oil changes like this can coke up the piston oil control rings and when this happens the engine WILL use oil.

I can’t even start to remember how many Subaru engines I’ve torn apart and discovered that while the compression rings were still free in their lands, the oil control rings were coked solid courtesy of longer oil change intervals.
E.G., compression good and still an oil burner.