Briggs 3.5hp Engine Issue?????

Well i have this briggs 3.5hp engine, was using it to cut a really large yard for its size. Went threw 1 tank of gas without stopping. When I let it rest a bit, i came back started it up and big smoke cloud came out for a few seconds and went away after about 15-25 seconds.
What would cause that?
Weak oil ring, or oil seeping past the exhaust valve guide. but it only did it that once. and it occasionally does it every once in a great while, but the mower is never been tilted when it does happen.

Possibly some leftover mixed gas in the gas can? Maybe running rich or float stuck- or carbon on the valves.

well it was straight oil burning cause i could really smell it, and it wasn't the carb running rich or anything so im not sure what its issue is. but i also know that i never have any oil mix in the gas cans for i have two deticated cans one for gas and the other for 2 strokes.
but idk

Really dont know. Maybe the oil was getting really hot and thin and got past the rings?

My old 12hp did that once, totally out of the blue, cold started it once, like any other time, and it puked out while reek for a good 30 seconds. Never did it again. Never found out what caused it.

maybe some little green men started a nuclear camp-fire in your exhaust and your's too chunk! maybe if we could just harvest this power.....

nah im just pullin yer leg, honest have no idea about this although my dads lawnmower 12hp castel garden did that once....

Did you tip it over to look underneath it? That'll do it. I also let my machines idle without a load on it for a lil while before I shut it off. It helps extend the oil life too.

no i didn't tip it at all, but i did happen to run out of gas, i was mowing a large yard with the thing. it does actually quite well for such a big yard and tall grass.