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Burning LOTS of oil - Can my engine be saved?

We bought a 2003 Toyota Sienna with 50k miles on it. We've had it for about six years and it now has 108k miles. It has never used much oil until about 6 months ago. I probably went longer than I should have between oil changes (don't ask me how long; I have no idea) and when I checked the oil one day it was probably at least 3 quarts low. Ever since then it has been burning about a quart of oil every 400-600 miles. It usually smokes out the exhaust on startup, especially after sitting for a while. I've had one mechanic tell me I need a new engine but all he did to diagnose it was start it up and watch it smoke. I changed the spark plugs this weekend and I've attached a picture of what I found. Is there any way to determine whether the problem is rings, valve guide seals, or both? Is there any hope for my engine or did I destroy it?
2592 x 1936 - 2M


  • The first step on an oil consumption complaint is to perform a compression test; both dry and wet. Compression and leakdown tests are not 100% definitive but it's all there is and is generally good enough to tell if there's a problem with rings/valves or not.

    On a good engine you should see readings in the 180-190 PSI range on the dry test. If this is followed up with a wet test and if the readings go up considerably then you can figure on the piston rings being worn or frozen in the ring lands.

    Running an engine low on oil and/or extended oil changes can also contribute to piston ring problems.
    As to valve seals, there is no test for those. They're a replace and pray item but should not be considered without doing the compression test first.

    Those plugs are utter garbage actually and should have been changed eons ago; platinum or not.
    If you do the compression test pay special attention to cylinders 1 and 2.
  • Spark plugs 1 and 2 look like the spark plugs that came out of my 1970 Plymouth, (180,000 miles) not good.

    I have replaced valve seals on Toyota's slant six (this engine is tilted with the rear bank facing the firewall). The usual complaint is oil smoke on start up, however your oil consuption is more than usual. Replacing the valve seals involves removing all four camshafts, not for the novice.

    Perhaps the unintended example of why not to follow so many examples of "fleet" vehicles that have been reported to go 10,000 mile between oil changes.
  • Before you condemn the engine, service the PCV system from end to end, not just the valve..If the crankcase venting gets plugged up, it can force oil back into the air-cleaner box and throttle body. This area should be DRY, no oil residue..
  • You're obviously burning oil. Like Caddyman said, service the entire PCV system. ok and Nevada are right about the problem likely being internal, like valve seals and rings, but I'd try one more thing. Get the engine good and hot. Change the oil using 5W20. Drive it like you stole it--hard--for a week--and change the oil again. Do this a couple of times and see if you can get some of that sludge/gel to break free. What have you got to lose other than some time and a case of oil?
  • How is your coolant level, are you loosing any coolant at all, even as little as a cup every couple of months? I ask this because that #1 plug looks like it might have some antifreeze contamination on it as well as oil burning.

    The first thing I would do is pretty easy. Remove the valve covers and check for sludge build up on the top of the head. Also check the oil drain back passages. These should be at the lowest points on the head, either at each end or in the center but on the exhaust side. The heat from the exhaust, especially when the engine is first shut down, tends to cook the oil coating the drain back passages causing them to get increasingly narrow until they can't drain the oil back as fast as it is being pumped up there.

    When this happens, the oil floods the valve guides and gets into the combustion chamber. If you see a lot of sludge under the valve covers, clean it out completely. Use scrapers and brushes and solvents as needed. Clear the drain back passages and clean them good. Then drain the oil, replace the plug and dump a gallon of solvent into the oil pan, pull the plug and drain into a fresh oil pan. If you get a lot of lumps, filter them out with a screen and dump it through again. Finish off with fresh oil and oil filter.

    If the oil gets dirty real fast after that, do another oil and filter change. Watch it close.
  • Just started experiencing a quart of oil consumed per every 300 miles on my 1990 Suburban, 215,000 miles, 350 cu. in. engine, 3/4 ton, C2500, automatic, 4 WD. No oil on driveway. No smoke on startup or while driving uphill, but a little on reving the engine while parked. Do all these suggestions above apply to my Sub for tracking down the problem., even the 5W20 oil flushes? Without having any diagnosis done, two shop want to stick in a rebuilt engine, i.e., $3500 to $4500.
  • Same as above the first step on an oil consumption complaint is a compression test; both dry and wet.
    And hopefully the person doing the compression test will be able to differentiate between real world numbers and the tripe that is published in the service manuals.

  • In 1964, before being drafted, my old 1953 Chevrolet used a quart of oil every 30 miles. I simply added a quart every 30 miles or so, even made a 1120 mile round trip that way. It also didn't especially smoke. Someone said later it was probably main seals.

    I came home from Fort Lewis about 10 months after being drafted, and put in a rebuilt engine and transmission, drove that car 2050 miles to Fort Lewis, and drove it a year or two after finishing my two years, then gave it to a brother and bought a new 1967 Chevy II.
  • Thanks to you both. The (30 miles/quart) sounds like your pulling my leg, Irlandes, but I appreciate your post.

    I've never done a compression test, let alone one wet and one dry. I guess I'll dig out my old Helm manuals to figure out how to do them and then try to differentiate between real world vs. service manual numbers. Can you give me some details, OK4450, on the proper way to do the test and interpreting the numbers correctly? If not, I'll submit a new thread.
  • Just remove all of the spark plugs, prop the throttle plate open (brick on the pedal would work), screw the compression tester into one of the spark plug holes, and crank the engine over for 4 or 5 revolutions. Note the reading and write it down. Repeat on all of the other cylinders.
    You should see readings of 180 or so on a good engine.

    This should be followed up with a wet test. This means going back and performing the test again but a small squirt of oil should be added to each cylinder before it's tested.
    Write down each reading on the wet test next to the one from the dry test.
    If you see a noticeable jump upwards in the readings during the wet test (say 20, 30 PSI etc) then this is a sign of a ring problem.

    It's also possible to have good compression and still have a ring problem. The upper 2 compression rings may be fine but the oil control, or wiper ring, may be frozen in place due to oil coking, any prior overheating episodes, etc and is not wiping the cylinder wall of engine oil on the piston downstrokes. Hope this helps and if you do the test you might post back with the numbers. Best of luck.

    (The reason I'm so critical of manuals, both factory and others, is that a lot of non-real world specs are published in there and I can only theorize is that these numbers are something a slide rule guy came up with. Erroneous compression numbers, oil pressure specs, you name it; a lot of it is flawed. I've got some factory Subaru service manuals that state 130 PSI of compression is the norm and that's not just wrong; it's absolutely ludicrous and downright laughable.)
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