BLKM3

I've been noticing this more and more frequently on startups that a cloud of white smoke comes out the exhaust. Not every startup but maybe like 1 in 4. Prior to my headers and full catless exhaust,
I don't ever remember this happening. What is the issue? Is something wrong with my car?

kimeran

My car also did this once in a blue moon, stock exhaust etc.
It eventually stopped on it's own

odonnks

Mine has done this once or twice during the first year I've owned it. There are many others that do the same.
I don't recall the cause but do remember that the occasional puff at cold start was nothing to worry about.

BLKROKT

I seem to recall something about valve stem seals leaking slightly, causing a very small amount of oil to collect in the combustion chamber when the car is at rest. Nothing to worry about as long as your oil consumption is ok and it doesn't get worse.

tfthach13

When the white puff of smoke does occur, are you pretty low on on your gas tank? It's happened to me a few times when my tank is below the reserve indicator.

If not, then it's probably some residual oil or what not that's being burnt off. As long as it's not a consistent white smoke coming from your exhaust, I think you'd be ok.

Mort

White smoke could be condensation. There is a lot of water in combustion and it condenses in the exhaust when the pipes cool down after shutdown and turns to steam as the exhaust first heats up. The colder it is outside the more it will happen and for a longer period of time.

Could also be a little oil sucked by the valve seals when the engine is shut down and the throttles are closed and intake vacuum is high.

Not really anything to worry about if you only see it on startup.

507AMG

Many past topics on this. I had/have 507 sedan and it has done this a few times. I did my first oil change at 3k and sent it in to Black Stone Labs. It was absolutely perfect. I write all this to assure you that it is very normal for this car/engine and is not antifreeze as some may state. I asked black stone to specifically look for antifreeze for this reason. 0% in the sample. I actually think it happens the startup following a brief startup when cold and then shut the car right back off.??

BLKM3

I wonder if it's because I have no cats or resonators. Sometimes this happens on cold or warm startups. Oil seems to be fine.