Car Burning Oil: Keep Topping Up, Fix It or Junk It?

A feeling that it uses a lot of oil is not enough to go on. Get a number from your own car.

1. Check the oil the right way

   Park on level ground with the engine off for a few minutes, and follow the dipstick instructions in your owner’s manual.

2. Fill it to the proper level and note the mileage

   Write it down with the date, along with how much you added.

3. Check at every fill-up

   Add only what it needs, and keep a log. After a few weeks, you will know how quickly it uses oil.

4. Compare with the owner’s manual

   Some manuals state what the maker considers normal use. Your mechanic can also tell you what is reasonable for this engine.

A leak is often the easier repair of the two, but do not ignore it. Oil on hot exhaust parts is a fire risk. Also try not to let it reach the ground where you park. Ecology’s used oil page directs households to 1-800-RECYCLE for where to take used oil, and our used oil and antifreeze guide covers more.

Ask a mechanic to narrow it down. These run from smaller to larger jobs, though it depends a lot on the engine.

• PCV valve or hoses. A clogged crankcase vent can push oil where it should not go.
• Valve cover gasket or other seals. Often a leak rather than burning.
• Valve stem seals. Often show up as smoke at startup.
• Turbocharger seals, if your engine has a turbo.
• Piston rings or cylinder wear. Usually means major engine work.

Questions to ask

• Is this engine known for using oil? Has the maker published anything about it?
• Did you check the PCV system?
• Have you run a compression or leak-down test? What do the results say?
• Is the oil harming the catalytic converter or the spark plugs?
• If I keep topping up, what should I watch for?

• Keep topping up

  Reasonable when the rate is steady, you check often, there is little smoke, and the shop finds no bigger problem. Keep records, and use the oil the manual specifies. This often suits a car you plan to keep only for a limited time.

• Fix it

  The better call when the cause is a confirmed, smaller part, or when the car is worth keeping and the quote makes sense against the value the repair adds.

• Let it go

  Sensible when use is heavy or rising quickly, compression is failing, other big repairs are near, or the only fix is major engine work the car cannot justify.

If the choice is major engine work, see our guide to replacing a blown engine for what to compare.

Topping up keeps the oil at a safe level. It does not cure the cause. Watch for these limits:

• If you forget, low oil can ruin an engine quickly. An oil warning light means stop as soon as it is safe and shut the engine off.
• Burning oil can shorten the life of the catalytic converter and spark plugs. Ask your mechanic what to expect.
• Heavy smoke is a problem of its own. Washington’s emission check program has ended, but rules on excess smoke remain. Our guide on the end of emissions checks covers what that does and does not change.
• A sudden jump in oil use means something has changed. Get it looked at again.

If it still runs and you sell privately, tell the buyer how much oil it uses and share your log. That honesty can help, since a known rate is better than a mystery. If the oil use has gotten serious, we buy cars as they are, running or not, and we pay cash at pickup after a free tow. Our offer is based on year and model, condition, demand for parts, weight and size, and towing distance. Learn more on our cash for cars page, or weigh it all in our repair or junk guide.