I let it set a while and got it out today to put the new front tires on it, and then I ran it hard around the field for a good hour, and it's not smoking hardly at all!
In fact, it smokes less than my Cub, you can't even see the exhaust most of the time - and it's not blowing smoke out the oil breather cap any more either! 
You can ADD some Seafoam to your oil and keep those rings free by running your tractor more often (even if it's just for a ride down a country road) 
