Jcru111

My a4 b6 1.8t lets out a puff of white smoke at start up from the exhaust. It does this maybe once or twice a week. Is this something to be concerned about? It just puffs out a puff and then doesnt smoke at all until a few days later where it will let out one puff of snoke again from the exhaust

turbo510

It shouldn't do that, but the cause determines whether it is worth being worried about. If the smoke is from oil (if you could get a whiff you might know) then that is typically from valve seal leakage. A "high-mileage" oil might help the seals in that case. If this is the issue, you can probably disregard it as harmless.

If the puff is actually coolant steam, which will disappear as it absorbs into the air (and will smell like coolant), this is often the first hint of a failing head gasket. You'll also begin to notice loss of coolant, and it can progress to the point that a cylinder fills with enough coolant to hydro-lock when starting the engine, sometimes bending a connecting rod. If your car begins to do this more frequently, I would crank the engine, then immediately shut it off as it fires. Pull the plugs, and if there are any coolant drops on the electrodes, plan on removing the head for inspection and a new gasket at the least.

Another cause for a puff of smoke, usually black, is an overly-rich mixture, usually along with a poor running engine- but your description doesn't suggest this one.

Jcru111

I have been having to put more oil in. The coolant seems to stay the same level. Thanks for the quick reaponse! I do have 185k on it.

Jcru111

The smoke lingers in the air after ward. Also what is a good safe high mileage oil

W261w261

Sure there isn't a little blue in the exhaust? Sounds like valve seals to me. As the car sits, the oil in the top end leaks down past the seals and into the combustion chamber. It burns off with a puff (at first) . If that's your problem, it will get slowly worse, usually ceasing as the engine warms up and the clearances close. In cold weather it will be worse also. Eventually, the smoke will be voluminous. I had a 3.0 BMW that over 3 years went from irritating to embarrassing.

turbo510

Stay with a major-brand synthetic, labeled for high-mileage engines, and you will be fine. Valvoline produces that type, would be a safe bet.

Jcru111

It just looks grey and white. So if it is leaking valve seals how long can i drive this before engine issues if i keep oil in it? Its at 185k and i will just drive it til it dies instead of put in thousands of dollars of work.

turbo510

Without knowledge of what causes the smoke, we can only guess. If oil due to leaking valve stem seals, that is more of an annoyance than an engine-wrecker, and many people would ignore that without further problems. However, if it gets to the point of always puffing out smoke after sitting a long time, pulling the plugs right after a start attempt should indicate either oil on the electrodes, or coolant.

W261w261

Fixing bad valve seals is not the end of the world. What happened with the BMW was eventually it got so bad that it was too embarrassing to drive, like there were no mosquitos alive behind me. It was the worst on startup. I didn't repair the seals because the unibody on the 3.0CS was rotting and was really unfixable (see "Karman, King of Rust.").