Grey Smoke From The Exhaust
Grey or bluish-grey smoke can mean the engine is burning oil, for example from a turbocharger or worn valve stem seals, or that unburnt fuel is passing through; on automatics, a leaking modulator can also burn gearbox fluid.
High risk
Have it checked soon. Burning oil damages the catalytic converter and can lead to low oil levels.
Short answer · What does grey smoke from the exhaust mean?
Exhaust smoke colour gives clues. Grey smoke sits between blue oil smoke and black fuel smoke. Oil leaking from a turbo seal or past worn valve guides burns grey-blue. A rich mixture or misfire can also produce greyish smoke. Watching the oil level over a few weeks is the simplest first check.
Safe checks you can do
- Check the oil levelA dropping level supports oil burning.
- Note when it appearsOn start-up, under acceleration or all the time.
- Check for an engine lightMisfire or mixture codes point to fuel.
Questions that narrow it down
- Is the car turbocharged?Turbo seals are a common source.
- Is the smoke worse after idling?Valve stem seals are typical.
- Does it smell of fuel?Rich running is likely.
Possible causes
Listed without ranking. Use the questions above to see which ones fit your car.
- Turbocharger seal leakOil enters the exhaust.
- Worn valve stem sealsSmoke after idling or on start.
- Worn piston ringsSmoke under load.
- Rich mixture or misfireFuel passes unburnt.
Questions about Grey Smoke From The Exhaust
Is grey smoke serious?
It needs attention; it usually means oil or fuel is burning where it should not.
Can I keep driving?
Usually for a while if the oil level is kept correct, but have it checked.