oil in air filter

[boo]

how and why does it happen?.
Have seen multiple post by members mentioning oil being sucked into air filter.
Is it because crankcase is not vented properly?.

[MaryK]

The crankcase and the rear gearcase are both vented into the airbox where the air filter also resides.
The vapors get recycled into the engine and burned.  The oil & water are supposed to condense and drain out through the drain tube.
Do you every pull the plug on your drain tube and drain out the condensate ? 
Many owners don't and the airbox accumulates too much liquid.  This also happens when the crankcase and/or the rear gearcase are overfilled with oil.
Best to pull the plug on the drain tube every 1000 miles or even 500 in the winter when more water condenses.

Scoot safely,

[boo]

The crankcase and the rear gearcase are both vented into the airbox where the air filter also resides.
The vapors get recycled into the engine and burned.  The oil & water are supposed to condense and drain out through the drain tube.
Do you every pull the plug on your drain tube and drain out the condensate ? 
Many owners don't and the airbox accumulates too much liquid.  This also happens when the crankcase and/or the rear gearcase are overfilled with oil.
Best to pull the plug on the drain tube every 1000 miles or even 500 in the winter when more water condenses.

Scoot safely,

Thanks a bunch. Your explanation makes perfect sense.
Mine is doing this.
When I took my scoot in for the 600 mile service, I think they overfilled the rear drive. When I pulled the fill plug on my rear drive, oil started oozing out.
I don`t think it is supposed to be that full.
I don`t think the correct measured amount would ooze out the fill hole.
I will pull the drain plug and check.
Thanks again.