Lawnmower burning oil, finally want to fix it!

It's been this way for at least seven years... but my Lawnboy mower (Tecumseh 5.5HP engine) has burned oil since I got it (used). It's not so bad when the engine is cold, but after it gets warmed up (20 or 30 minutes) or if it is operated on even a modest incline or if it's operated with a real heavy load (chopping piles of leaves for example), huge clouds of blue smoke come out. Especially on moderate slopes, the smoke is so thick that if there's no breeze I have a hard time seeing. Huge thick coulds. It also blows a lot of smoke when it runs the gas tank dry and the engine runs rough for ten or fifteen seconds. (Almost like the engine is running for a while just on burnt oil! Is this even possible?)
There is no apparent oil leak onto the garage floor when it's sitting there.
Rate of consumption: about half a quart of oil for every gallon of gas. That means 3 quarts per summer, roughly.
If I let it run low it doesn't seem to burn oil as bad, but I like to keep it filled to the top of the range on the dipstick. Pretty much every time I use it, it burns half a pint, enough to take the level from the "full" to well below the "fill" line. The overall capacity is probably 1.5 pints.
Every spring it's hard to start and I replace the air filter and find the spark plug completely fouled so I replace it too. I also change the oil every spring. But otherwise it runs very reliably and has had no other engine maintenance.
Now it's been this way for 7 years and I've never done anything about it - mainly because it only costs a couple bucks a year just to put more oil in and another two bucks for a new spark plug. Is this an endemic problem with Tecumseh engines, is this a sign that it needs a ring job/rebuild, or is there some valve that's stuck that might cause this?
Tim.
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i think there is a crankcase breather on the engine, if not working it can cause this. ive replaced a few. if you rebuild it, buy the service manual, ittl save you alot of time, lucas
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As DS suggested, sounds like problems with the breather valve.
How about buy a quart of "outboard motor oil" and use that? At least it burns more cleanly tha 10W30 or HD30.
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I'm more surprised that an older lawnboy mower has a tecumseh motor on it. OMC NEVER used them and when toro took over, they have their own line of motors.
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snipped-for-privacy@gmail.com wrote:

Plus, to the best of my knowledge, Lawnboy always used 2-cycle engines???
OP did note he got it used...sounds like former owner replaced original w/ generic to me...
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lawnboys have had the 4 stroke choice since 1992 i know for sure. lucas
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