burning coolant=white smoke, burning oil=blue smoke, injector stuck open=black smoke. with the car cold, open the coolant cap and start the car, look for bubbles in the coolant: this would be exhaust gas getting past the head gasket(s). also look for coolant in the oil, the oil will look like chocolate milk. it is possible to have a blown headgasket (or worse) and get no cross contamination of any fluids. if you are leary of local shops, do a search for leakdown test and compression test, purchase the gauges and have at it yourself, might be the way to get to the bottom of this.
[I]"Winners never quit, quitters never win, those that never win or quit are idiots."[/I]