Small Engines (Lawn Mowers, etc.): white smoke, crankcase breather, briggs and stratton

Question
I have a 15 hp Scott's Exclusive by Briggs and Stratton, model 28q777, type 062101. Upon starting it bellows white smoke for about 5 minutes. It runs perfectly except for the smoke. Doesn't stall. I think this began sometime ago as I would occasionally see a puff of white smoke if I was mowing on an incline.

Answer
HB

Generally billowing clouds of white smoke are from one of two things. Either the crankcase breather has failed or the oil is contaminated.

The crankcase breather vents the gases and excess pressure from the crankcase and sends them through the carburetor to be burnt in the combustion process. Some breathers are nothing more than a reed valve that opens and closes as the pressure changes inside the crankcase from the piston's movement. If this reed breaks, bends or otherwise fails, then excess oil is pulled into the carburetor and the result is a lot of smoke. Other breathers are screen or filter type and when they become too fouled or broken down to function, same result, lots of smoke.

Diagnosis is done by looking for two things, oil in the air cleaner/carburetor and black oil soaked or heavily carboned spark plugs. Since oil is being fed directly into the cylinder, the plug will foul very quickly and probably also affect engine performance. Breathers can fail at any time, often they will fail over the winter as the oil that's built up on and around them solidifies and just generally plugs things up.