My daughter’s Scion has 235,000 miles on it, runs great, instant acceleration and has no problems reaching 75-80 mph on the interstate. The problem is that after you have used half a tank of gas, or less, the oil is a quart low. This only happens at high speeds. If you drive around town you can use a whole tank of gas and not use any oil. There doesn’t seem to be any leaks even after the car sits in the same spot for a week or more. Local mechanics have differing ideas. I have not tried adding leak stop to the crankcase. Should I try that? Any other suggestions?
guessing, 15 gallon tank, 30 MPG, that is about 200 miles per quart of oil lost. That is a LOT of oil.
sounds like you need an engine rebuild or a new engine. What color is the exhaust?
Does this have a PCV valve? If so this would be the first thing I would look into. You are putting more load on the engine and therefore more blowby at high speeds. This isn’t exactly a young engine so it MAY just be wearing out but if the PCV cannot vent, it could cause excessive oil consumption. The PCV is cheap though so that would be my first step.
There are various snake oil type flushes to clean out the top end and possibly free up sticky rings. You might try some of these if the PCV doesn’t work as you don’t have a lot to lose at this point! Seafoam sucked in through the intake would be my first step.
Has the oil ever been neglected in this car?
The problem is often caused by a blocked crankcase ventilation system.
The fact that you lose no oil around town but lose it only at high speed coupled with the miles on this car makes me suspect that you are building too much crankcase pressure at high speed and blowing it past the rear mail seal. Try changing your PCV valve.
What ideas do they have and has anyone actually done any tests ?
I don’t know the model or if it even has a PCV valve. These are usually cheap and maybe a 5 minute job to swap. I would just buy one at a parts store and change it if the mechanics don’t know.
Yes, it is a gamble of maybe $15-20 but that is better than the alternatives. It is cheaper than paying someone to diagnose this as well.
I had a car that experienced the same symptoms as yours. It was a 3 cylinder Geo Metro. The engine had been run with a huge gap in the air cleaner assembly by the previous owner for who knows how long… There was enough sand and dirt in the intake that I could scoop it out. Anyway, the car burned oil and LOTS OF IT! We are talking a quart every 100 miles or more! Somehow it still ran great and was getting 52MPG but I swapped the engine once I found a good donor car.
What model Scion?
Scions use Toyota 4-cylinder engines . . . some of which have had severe oil consumption problems, due to pistons and rings
I also seem to recall the 2007 Camry being especially bad about this. I had a buddy with one of these. It didn’t help that his wife wouldn’t do anything except mention to him that the “low oil” light was on when it was about dry.
I wonder if they used the same engine. What model is this?
Check out https://www.carcomplaints.com/Scion/tC/2007/engine/ This model had lots of issues with oil consumption.
The PCV valve is important when the engine is running at low RPMs. At highway speeds the larger vent from the engine to the air filter housing carries a great deal more volume and is usually the cause of extreme oil consumption at high speeds.
Add this to the engine oil.
If the oil consumption slows down/stops, the problem is worn rings/cylinders.
I believe some of the bigger Scions used the 2.4 liter 2AZ-FE . . . the one that has been known to consume a lot of oil
I am not really for oil additives but they probably can’t do any more real harm to this engine. Try the PCV valve first and then the additives if that doesn’t work. You might see if they can free up stuck rings and such. If the 2.4L, you may be out of luck. Just keep an eye on the level and make sure it doesn’t drop too low. You will probably get a lot of life out of it but the inconvenience will get old fast.
I believe the engine could last a few more years, if op gets in the habit of checking and topping off as needed, which will probably be every week
I had cars like that in the past, and they were reliable and even regularly passed tailpipe smog inspections
If stuck rings are involved, Marvel Mystery Oil in the fuel may help.
For stuck rings, I believe you put it in the crankcase.
That makes more sense. It can be used in either or both, say its instructions. I used it for a while, in the gas, to stop preignition knock in my 1984 Cavalier and it seemed to work. Some time later when I had the head into machine shop they commented on how clean (no deposits) it was. I also changed oil within the recommended time/mileage specs.
Good ideas above. If I had that problem I’d probably want to do a compression, intake manifold vacuum, and oil pressure test to get some more data to base a decision. I’d also want a valve-stem seal visual test; i.e. does it produce an unusual amount of smoke out the exhaust pipe only during start-up? My guess however is the problem is caused by an accumlated 235K miles of internal engine wear, which only an engine tear-down & rebuild will be able to address.
Thanks everyone for your suggestions. There is no smoke coming out of the exhaust and it is the 2.4L engine and it is a TC. No testing has been done. My daughter lives 9 hours away from me and I just became aware of the problem. I do know she has been faithfully keeping up with routine maintenance. I think I will try changing the PVC valve first. Sounds like it would be worth a try.
Thanks for that information
The car DOES have the engine that is known for having excessive oil consumption due to piston and ring issues
But change that pcv valve first
Even if the pcv valve doesn’t help, the engine still has some good years left, provided your daughter diligently checks and tops off engine oil, possibly every week. Make it a routine