Why does a 19.5 hp kohler engine on a Craftsman lawnmower smoke real bad only once in awhile?

I have a 1997 Craftsman Gt 6000 Lawn Tractor that runs great except everyonce in a while the motor bogs down and the blue smoke just rolls out of the thing. It has a 19.5 hp Kohler Magnum engine. it acts like it is sucking oil from the crankcase or something. other than this the motor runs fine.|||I had this problem last year. First, check the oil and be sure that it isn't something minor like that. The problem with my mower was that one of the lines (can't remember which) was old, dry, and cracked which was causing the engine to smoke and die fairly frequently. At first it started bogging it down, but the longer it went without fixing the worse it got. You're best bet would be to take it to a mower mechanic and get it checked out.|||You probably should get it a nicotine patch. Smoking is a bid habit for a lawn mower engine. It can shorten its life.|||It could be you are mowing on the side of a hill of something. I have one with a B%26amp;S 16 HP and it does the same thing. Sometimes I think that I have added too much oil, but it shows okay on the stick. I live in a town with a lot of hills though and I know the hills do it. Again it is only at times.