Smoke and smells
Blue smoke from the exhaust: the engine is burning oil
Blue or blue-gray smoke that smells of burnt oil means oil is getting into the combustion. It usually comes from the turbo, the valve stem seals or the piston rings, and it makes the oil level drop between changes.
See a garage soonSmoke and smells
Reviewed by Daniel Morales, founder of Reprorace SL, on
Is it serious? Can I keep driving?
Carefully, and only as far as the garage. You can drive to the garage while checking the oil level often. Do not leave it: burning oil fouls the spark plugs, the catalytic converter and the particulate filter, and if the level drops too far the engine is left without lubrication.
A careful, general answer: only someone who inspects the car can say whether it is safe to drive. When in doubt, stop somewhere safe and call for assistance.
Most likely causes
- Turbo: with worn seals, oil passes into the intake or the exhaust; the smoke usually shows when accelerating.
- Valve stem seals: smoke on start-up or when accelerating after coasting downhill.
- Worn piston rings or cylinders: constant smoke and high consumption, often with low compression.
- Too much oil: a level above the maximum can let the engine draw it in.
- Crankcase ventilation: a blocked ventilation valve pushes oil vapor into the intake.
Listed from more to less common in general; on your car they may be different. A fault-code reading and a check at the garage confirm which one it is.
To understand it better: How does a turbocharger work and what does P0299 mean? What is a catalytic converter and why does it fail?
Car system: Engine and lubrication
What you can check yourself
Check the oil level with the engine cold on level ground, and note how much you top up.
Note when the smoke appears: on start-up, when accelerating or all the time.
Make sure the level is not above the maximum after an oil change.
With the engine cold, look for oil in the turbo hoses or the intake.
Safe checks only: with the engine off and cold whenever you look under the hood, without taking anything apart and without touching hot or moving parts.
How the ECO-LITE helps diagnose it
Plugged into the OBD socket, the ECO-LITE reads the fault codes of the control units that answer, with the freeze-frame data captured when the fault happened, and shows live data on your phone or computer. With your permission, your garage can see them remotely before you bring the car in.
What to look at here: boost pressure and misfires; catalytic converter efficiency if it has already been affected.
Frequently asked questions
How much oil is it normal for a car to use?
It depends on the engine and how it is used: the handbook gives the acceptable consumption. If you keep adding more or see smoke, have it checked.
Will an additive fix it?
It may reduce the smoke for a while if the cause is mild, but it does not repair a worn turbo, valve seals or piston rings.
Does it damage the catalytic converter?
Yes: burnt oil leaves deposits that reduce its efficiency and can end in a code such as P0420.
Keep reading
- Engine and lubrication: how they work and what fails
- Car using oil: when it is normal and what to do
- White smoke from the exhaust: what it means and what to do
- Black smoke from the exhaust: causes and what to do
- Car symptoms: what they mean and what to do
- Check engine light on: what to do
- How to read and clear your car's fault codes
- OBD fault codes: what each one means