My Cadillac with northstar started blowing blue smoke from the tail pipe when I was sitting at a light. The other problem is engine stalhs out when shifted into reverse.

SOURCE: white smoke?

It's just condensation. Water will also drip from the pipe.

The colder it is, the worse the 'smoke' will be. I was in Vernal, Utah earlier this week, drove through -18*F weather, my truck never quit blowing white smoke.

And NO IT IS NOT YOUR HEADGASKET

SOURCE: f-150 4.9 lt .once it starts, blowing heavy black smoke

Sounds like its flooding(excess fuel)Try squeezing the main fuel line enough to allow enough fuel through for engine to run smoothly if that improves running of engine either fuel pump needs replacement or pressure relief valve has failed or has no vacuum to activate it.Dirty or failing injectors can also cause your problem,try putting a can/bottle of injector cleaner in fuel tank to see if it improves running of engine.Air flow meter can also be an issue.A few potential reasons foryour problem and too hard to lock it down to a single cause without the vehicle being in front of me to do the appropriate tests so have just provided the basic causes and hope your able to take it from here and solve the problem.Good luck

SOURCE: my 2002 jetta blows blue smoke a lot of blue smoke

I had the same problem with my Passat 2000 , I started to put "Smoke no more" the next day after every oil change and worked pretty good. Every bottle coste me about $4 at Pepboys...

SOURCE: Constant smoke from tail pipe.

If its smoking that bad you should be able to tell if its oil or antifreeze by the smell, stand behind the car as its running, if its white and you smell a sweet smell its antifreeze if its blue and smells like a oil refinery its oil.

SOURCE: 1985 f250 with a 460 gas motor blows blue/white

Blue --is Oil
White- is Coolant

Bad intake gasket or head basket