Small Engines (Lawn Mowers, etc.): 17hp Briggs&stratton engine, engine model type, briggs stratton engine

Question
Wife had an incident mowing lawn (scotts s1742 lawn tractor) where she claimed the tractor started billowing smoke from the engine. Upon inspection I didn't notice anything unusual, except was a bit low on oil. Happened to overfill a bit so when I went to drain some oil out, I noticed the oil viscosity was that of gas and smelled heavily of gas??? Is this normal?? My fear is something inside engine cracked and mixed the gasoline with the oil. Is that possible??

Answer
Usually this is caused by a leaking carburetor inlet needle.  What is the engine model, type and code number?  I need the engine numbers to look up your carb.

It is also possible that a small piece of dirt/debris or even a small drop of water happened to get past the fuel filter and temporarily cause the needle to leak.  A leaking carb inlet needle will allow fuel/gas to enter the engine oil through the intake valve.

Regardless, I would clean the carb, fuel system and replace the inlet needle, and of course change the oil.  

Eric