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Puff Of Smoke On Start-up

A blue-grey puff of smoke right after starting, especially after the car has stood overnight, that then clears, usually comes from oil seeping past worn valve stem seals or a turbo seal.

Normal risk

Usually not urgent. Monitor the oil level and have it checked if the smoke increases.

Short answer · Why does my car puff smoke when started?

When the engine stands, small amounts of oil can seep past worn valve stem seals into the cylinders or drain into the turbo. On start-up this oil burns in a quick puff of blue-grey smoke, then the smoke clears. It is a sign of wear rather than an emergency, but oil consumption may increase over time.

On this page

Safe checks you can do

  1. Note when it happensMostly after standing for hours: valve stem seals or turbo.
  2. Check the oil level regularlyTrack how much oil is used.
  3. Look at the colourBlue-grey means oil; white and thin is condensation.

Questions that narrow it down

  1. Only after long standing?Typical of valve seals.
  2. Is the car turbocharged?The turbo seal is another possibility.
  3. Is oil consumption increasing?Wear is progressing.

Possible causes

Listed without ranking. Use the questions above to see which ones fit your car.

  1. Worn valve stem sealsOil seeps when standing.
  2. Turbocharger sealOil drains into the turbo.
  3. Worn valve guidesSimilar to seal wear.
  4. Overfilled oilCan push oil into the intake.

Questions about Puff Of Smoke On Start-up

Is this expensive to fix?

It depends on the engine; valve stem seals can sometimes be replaced without removing the head.

Will it get worse?

Usually slowly. Monitor oil use.