Why is blue smoke coming from my exhaust?

Blue or blue-gray exhaust smoke means the engine is burning oil. Common causes are worn valve seals, worn piston rings, a clogged PCV valve, or — on turbocharged cars — failing turbo seals.

Cost range: $20–$3,000. Severity: medium. Safe to drive? Drivable, but check oil level frequently. Don't let it run low — engine damage compounds quickly.

Most likely causes

1. Failed PCV valve — Cheapest cause to rule out first. A stuck PCV pulls oil into the intake. $20 part on most cars. ($20–$100, common)
2. Worn valve stem seals — Blue puff on cold start or after coasting. Repairable without removing the head on many engines. ($400–$1,500, common)
3. Worn piston rings — Continuous blue smoke, especially under acceleration. Compression and leak-down test confirm. ($2,000–$4,000+, less common)
4. Failing turbocharger seals — Blue smoke under boost, oil in the intercooler piping. Turbo rebuild or replace. ($800–$3,000, less common)