Overall Mystery: Why is my car going through oil so quickly and where is it going?
Background:
We purchased a used 2002 Subaru Outback at the end of July of this year, after our car was totaled by another driver in a wreck this summer. This new-used car, dubbed Scooby Doo the Subaru, had about 105k miles at the time of purchase and was given a clean bill of health on a pre-buy inspection by a generic mechanic in the area.
About six weeks ago (early-October) our oil light started to flicker on when we stepped on the breaks. Soon it was on consistently so we checked the oil. We were completely out! We added 3 quarts and were good to go. We brought the car in for a routine check-up to our very reliable mechanic about 3 weeks ago and mentioned the issue. They checked the oil and it was already down by about half. They checked for leaks (finding none) and asked the usual questions:
Are there oil stains in your driveway? Answer: NO
Has there been smoke coming off the engine? Answer: NO
Have you smelled anything weird while driving; a burning smell, for instance? Answer: NO
They changed the filter which was dirty but not overly so, did one final overall check for leaks or clogs, etc. Not finding any they topped off the oil and said to come back in a week to check the level. A week later, the level on the oil seemed normal so we went on our way.
Last week, the oil light started flickering on again when we brake. Brought it in…totally out of oil again. Another inspection and there are still no signs of leaks, clogs, etc and the filter is clean. The mechanics say we will have to replace the engine. Their only thought is that somewhere in the engine is getting too hot and the oil is just burning up on contact. Over time, they think this will cause a clog and make it go completely kaput. The mechanics think we can roll along fine with consistent replacement of the oil but that it won’t last long. Where is all the oil going and if it’s being used up, how and why? Is there an easier/less-expensive fix than replacing the whole engine??
So, to the Daphne’s, Fred’s, Velma’s, and Shaggy’s out there…please help solve this mystery of our little Scooby Doo the Subaru.
How many miles with it going off the stick like that? You really should check that car DAILY if it consumes oil. An oil light flickering on a Subaru is not a warning light and to fill up at your next convenience – It is an indication there is no oil pressure. It is the engine’s scream for help. Very often if you see the oil light it is too late. Apparently, you’ve been lucky.
If you’re losing oil, CHECK THE OIL VERY FREQUENTLY YOURSELF.
Oil just doesn’t disappear. Oil doesn’t just burn. It would have to get horribly hot for that to happen.
It is going somewhere.
When you open the radiator cap (with the car COLD so you don’t get hurt), do you see any oily residue float on top? When you check the dip stick, do you see any milky substance in the oil?
If so, you likely have a blown head gasket. It is actually a common problem in Subarus of that vintage, although 2002 is towards the end of the problematic vintage. Let’s hope it is not that because it gets expensive very quickly.
A bad PCV could cause the car to burn oil but I would hope your mechanic would know to check that.
You don’t see any plumage of smoke behind your car when you accelerate, do you?
Subarus have had problems with something called an ‘oil separator cover’ but I think those were earlier cars. You’d also likely see oil seeping out where the engine meets the transmission - and you say it doesn’t leak.
It’s probably burning oil and the catalytic converters are catching it. That’s why no smoke. Eventually the cats will plug up and running the engine very low or out of oil has damaged it further.
The first step in inspection of a car should be a vacuum test and compression test. This could have weeded out a piston ring problem from the get-go.
It takes 10 seconds to connect a vacuum gauge and read it. Depending on that reading a decision could be made as to whether to proceed with a compression test or throw in the towel then and there.
I’m actually surprised that all they did was ask questions. You DID tell them the engine had been run totally out of oil? Or did you neglect that detail?
You need to start with a compression check, wet/dry. I’m willing to bet that the engine’s cylinders are shot, probably scored. You cannot run an engine dry without expecting damage. You cannot run an engine dry TWICE without almost GUARANTEEING damage.
Sorry to be the one to have to break the news. Let us know how you make out with the compression check.
You need to take the first steps. You need to learn where the dipstick is, how to remove it, and how to check the oil. Then you need to start checking the oil level every time you fill up the gas tank. You can do that while the tank is filling.
Carry an extra quart of oil and learn how to add oil to the crankcase. When you find that you are down a quart, add the quart and record the mileage. Pretty soon you should be able to determine the oil consumption rate.
If you are using less than one quart of oil per 500 miles, you may not want to do anything more than just keeping the crankcase full and getting regular oil changes. If you are getting less than 500 miles to a quart of oil, then you will need to determine the cause.
You are either leaking oil or burning oil. Just because you don’t see oil drops on the driveway or smoke behind you doesn’t mean that its not there. If it is leaking, the bottom of the engine will be wet with oil. You or your mechanic will have to get the car up on ramps or a lift and look under there. Opening the hood is not enough.
If oil is burning, you may not notice the smoke cloud but it might be visible to drivers stuck behind you in traffic. Sometimes the smoking only occurs when you are decelerating or going downhill, sometimes it only smokes when accelerating or going up hill. It depends on what is causing the oil to burn. As OK4450 pointed out, if the oil burning is not too much, the cats are finishing the burn off so the smoke is invisible.
“About six weeks ago (early-October) our oil light started to flicker on when we stepped on the breaks.”
Shoulda checked the oil level right then and there.
I haven’t read any further before posting this (I have a pretty good idea what follows.)
But I will press on.
Three weeks (or even days) of the oil light flickering is gross negligence.
I have no idea why the oil light only comes on when y press on the brakes – a look-see at the wiring harness schematic might explain this – but the oil has to be going somewhere. Since it isn’t dripping onto the pavement, about the only other places it can go is into the cooling system or burned in the cylinders and sent out through the cat and exhaust pipe. Check the coolant for signs of oil. And check the last inch or two of the car’s exhaust pipe for any oil residue. (When the engine is cooled off of course.) As mentioned above, a compression and/or leak down test would prove/disprove at not too much expense to you some of the theories mentioned here.
If the oil loss rate is more than one quart in 500 miles, I think you are probably looking at a replacement engine in your near future. Replacement engines are surprisingly inexpensive for what you get, but they will set you back a bit. So budget correspondingly.
Due to the design of the engine, engine oil can leak into the transmission area and make it seem to disappear. Check to see if that has happened. If it has then you are going to have to repair the engine. From the amount of oil you have lost I wouldn’t be surprised if that is what is happening here.
The oil light can come on in a worn out engine when the brakes are applied simply because the engine drops to idle when the foot comes off the gas and the lubrication system momentarily loses pressure.
In the OP’s car he was just plain out of oil. More than once. With that much internal damage he’s probably just on the cusp of maintaining proper pressure. My guess is that oil…when he DOES add it…is flowing past the bearings like water through the gates in the Hoover Dam.
Oil consumption due to whatever reason is probably why the previous owner unloaded the car and it could be that the prior owner also ran it out of oil.
The current owner doing the same certainly did the engine no favors.
The reason the light comes on when he applies the brakes is simply that there is only about a half inch of oil left in the pan. He’s down over three quarts in what is probably a 4 quart system. The oil sloshes forward and exposes the pickup tube to air, which is what it sucks instead of oil, and the light comes on. This in addition to what mountainbike and OK4450 said.
I can’t believe you can loose as much oil as the OP stated he did without some sort of trace of it. The only place it could go without leaving some sort of sign in the engine is into the transmission. I’ll bet the tranny fluid is contaminated.
You guys are not helping. Clearly said, THEY TOOK THE CAR TO A SHOP, & IT WAS INSPECTED THERE. The shop checked everything you guys have said. Unless you have a Subaru, you can’t understand the question. The oil is a mystery.
NO SMOKE
NO SMELL OF BURNING
NO OIL IN THE OIL PAN
NO OIL ON THE ENGINE
NO OVER HEATING
CAR RUNS GREAT
JUST NO OIL AFTER A GOOD FEW WEEKS
You also do not seem to understand that an engine losing oil is only losing it one of two (or possibly both) ways.
One is obvious external leaks.
Two is burning oil past the piston rings or valve seals. You say no smoke. That’s easily explained. It gets caught up in the converters, turned to charcoal, and slowly spit out the exhaust as very fine soot; not smoke.
As someone who has been into many Subaru top ends my gambling money would be on seized oil control rings either due to infrequent oil changes or overheating.
Where does it say the shop did a compression check? Did I miss that? By the way, it’s entirely possible for compression to be great and still have an oil consumption problem because while the compression rings may be good the oil control rings are not.
Yeah, had me going there and then saw it was six years ago. Sheesh.
My Olds diesel was down to using a quart every 300 miles and I drove 100 miles a day. Oil light never came on because I put oil in it every other day. Out the tail pipe. No smoke. All it takes is a drop or two every thousand revolutions to burn a lot of oil.
My Riv with a leaky pan gasket would also go through a quart every week until I fixed it. Only the low oil level (comes on when a quart low) ever came on because I checked the oil.
