Skip to Content

Blue Smoke from Exhaust

See blue smoke puffing out the tailpipe? That’s not cold morning steam — that’s your engine burning oil. And an engine that eats oil won’t live long.

Why It Happens

Blue smoke means oil is sneaking into the combustion chamber where only fuel and air should be. Worn seals, tired piston rings, or a bad turbo let oil slip past and burn. The result? A smoky exhaust and a shrinking dipstick level. Ignore it and you’ll eventually starve the engine of oil.

Most Common Culprits

  • Worn valve seals — oil drips into cylinders on startup.
  • Tired piston rings — oil gets past, constant blue haze.
  • Turbo seals (on turbo cars) — smoke under boost.
  • PCV valve failure — pressure forces oil into intake.
  • Overfilled oil — crank whips it into smoke.

What You Can Check

  • Check oil level — dropping fast = confirmed oil burn.
  • Note when it smokes — only on startup? Likely valve seals. Constant? Rings. Under boost? Turbo.
  • Smell it — blue smoke stinks oily, not sweet (coolant) or fuel-rich.

What a Mechanic Will Do

  • Compression or leak-down test to check rings.
  • Inspect valve seals and guides.
  • Check turbo for shaft play and oil leaks.
  • Test PCV system for blockage.

Rough Damage to Your Wallet

  • PCV valve: $80–$200.
  • Valve seals: $600–$1,200.
  • Piston rings/rebuild: $2,000–$5,000+.
  • Turbo replacement: $800–$2,000+.

When to Park It

A faint puff on startup? You might limp it along topping oil. Clouds of blue when driving? Park it. Oil burners don’t get better on their own, and one dry run will finish the engine for good.