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Bluish smoke indicates the engine is burning lubricating oil. It is a symptom not to put off: as well as oil consumption, it damages the catalytic converter, lambda sensors and DPF.

When it appears (and what it suggests)

• On a cold start: worn valve guides or valve stem seals
• On the overrun, when changing down: valve guides or excessive crankcase vacuum
• Under acceleration and load: worn piston rings or cylinders
• Always, with a turbo: turbo oil seal or excessive crankcase pressure

Most common causes

• Turbo with excessive play drawing in oil
• Clogged crankcase breather (oil separator)
• Piston rings stuck by carbon deposits
• Valve guides and stem seals hardened with age
• Oil level too high after over-filling

What to do right away

• Check the real oil consumption every 1,000 km
• Check the crankcase breather: a frequent and cheap cause
• Have a compression and leak-down test done: it tells rings from valves

How MasterTuning helps

We do not replace parts by trial and error: we read the real values from the ECU (pressures, flow rates, corrections, temperatures) and identify the component responsible. Then we repair and recalibrate the software where needed. Centres throughout Italy.

Read more: find an installer · contact us · vehicle database

Does your car have this symptom? Book a diagnosis at your nearest MasterTuning centre.

Frequently asked questions

How much oil consumption is normal?

Many manufacturers quote up to 0.5 litres per 1,000 km as tolerable, but a sudden increase in consumption should always be investigated.

Can blue smoke be caused by the turbo?

Yes: a turbo with excessive play draws oil from the lubrication circuit and sends it into the intake.

Does burning oil damage the catalytic converter?

Yes: oil residues poison the catalytic converter and lambda sensors and load the particulate filter.