The oil cap on top of my push mower's 6HP B&S engine "unlocks" with a quarter turn has an attached dipstick. Apparently, the oil cap unscrewed and lifted while mowing under some shrubs. This evidently caused oil to spray out the open fill port, onto the underside of the open dipstick cap, and back down onto the engine. Hot oil drenched the motor, entered the rotating screen, and even pooled a bit on the mower deck. The air filter is covered and didn't get sprayed. I didn't notice the problem until excessive smoke started spewing out the muffler. A bit of smoke rose from the top of the engine as well. I only noticed the loose oil cap after allowing the engine to cool. Luckily, the oil level remained in the dipstick's crosshatched area, as it was slightly overfilled to start. The next day, I wiped down the mower (difficult to clean the rotating screen) and started the engine. Smoke began puffing out the muffler within seconds. Is this a problem, or should I just let it run and spew smoke?