N54 puff of blue/white smoke on startup?

[ManiacGT]

So I asked the other half to move the car back into the drive today as I was covered in paint from DIY. As I stood behind the car, the OH started it up. The usual N54 twin exhaust loud note was followed by the usual click as the right side exhaust flap closed to quiet it down. The engine had been running for around 1 second before the valve closed as usual and as the valve closed on the right side tailpipe I noted a small puff of white/blue smoke from the left tailpipe. So the weird thing to me is that if this was oil leaking into the cyls somehow, that white/blue smoke, I'd expect, would be puffed out as soon as the engine started. In this case the puff of smoke was 1-2 seconds after the engine had started.

It was a very small puff of smoke, but I noted it nonetheless. Now I'm quite fastidious about the car and it uses no oil that I'm aware of (26K miles) so I'm wondering if this little puff of smoke is normal ish and I've just never seen it because I've never been behind the car when someone else started it up.

Any N54 peeps on here that could comment? Reading online it could be anything from normal to turbo seals, valve seals etc etc. The car does do very very short journeys every day and I'm wondering if these short journeys could be causing premature wear somewhere. Quite how I'd address that anyhow is another matter.

[Alext]

Have a friend follow you and floor it. See if they can see any blue or white smoke then. Could be a number of things. Blow-by for example.

A little smoke on startup probably isn't concerning. No mayonnaise under oil cap?

[Kessler35is]

All engines use oil, you can not prevent it. Oil will always make its way around the ring in a minor way since every ring has a cut in it, also PCV allows oil into the intake.


If it was bad enough that it was blowing smoke while driving you would have noticed it by now. You would have seen that white cloud or caught the smell.

Also remember because of the PCV system you are always recirculating the oil vapors into the intake and you could of burnt a drop or two of oil that way.

The hotter you get the oil and the harder you drive the more you will burn via PCV.

Smog control is a joke and lame system, but the feelgood's want it.

[nicknaz]

You could get an oil catch can. Might help.

As others have said, I wouldn't worry about it too much. If you are putting in a quart of oil every 7500 miles that is one thing (I think even that might still be in spec, per BMW) but a random puff of smoke is not a big deal

It might also just have been condensation

[bigendbob]

I only have the 23i, but i do notice how dirty the tail pipe gets. Could BMW engines generally burn some oil and you as you say never been at the rear end at start up.