My Car Has Blue Exhaust Smoke When I am at Idle – What Causes This?

Reader Question Hi Austin,

Thanks for taking the time to create your site – its invaluable!

I have a problem with my car – a Mitsunishi (I think he meant Mitsubishi) Magna 1995. It runs fine, but when in traffic for any length of time (around 15 monitues) lots of blue smoke starts to come from the exhaust.

After moving again for about 1-2 minutes, the smoke goes away. When the smoke happened, the AC was on, but the temperature gauge was still at normal, and the engine seemed to be turning fine without any signs of overheating. No other indicators came on on the dashboard.

The engine oil is at normal level – I checked the radiator and it needed approximately another 0.75 litres of water adding.

If you have any ideas on what this may be, I would be very aprreciative.


Thanks for your kind words Simon. Did you read my article about exhaust smoke? Exhaust Smoke

If you are continually adding water to the radiator I would definitely have a cooling system pressure test done to look for leaks. Usually water or coolant will produce a white looking smoke (steam) from the tailpipe.

If the smoke is truly blue in color, AND the smoke is coming from the tailpipe, it is probably due to oil getting on the spark plugs.

This can happen because of internal engine seal or gasket leaks. Using a thicker weight engine oil might help slow down the leak, and some oil stop leak products on the market might also help slow the leak.

The correct repair for internal oil leaking unfortunately is to remove the top half of the engine and replace some seals and gaskets…which is costly.

If the smoke is coming from under the car or under the hood area, you might have a fluid leak which is leaking on the hot engine and or exhaust and producing smoke.

Austin C. Davis

Posted in: Exhaust Smoke

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