I have a 185 John Deere riding lawn mower, fairly old. It recently started to gush out smoke. Its mostly white, with a tint of blue and it leaves a sort of oily residue behind. Thinking it was to much oil as I had just put some in, I drained it of all the oil and added a quart. Figuring maybe not full, but at least enough to keep it going. It looked good for about 5 minutes, as soon as I turned on the blades though it sputtered and started with the smoke again. I’m at a loss as to what to do.