Thanks for the information, Engine oil is JD Plus 50 ll 15W40. It smokes a little blue during warm but that is normal for any diesel. What concerns me is when I am out mowing in the open yard the exhaust appears clear but when I am mowing up against a building, on the exhaust side, then I can see bluish exhaust. Then when I let it sit and idle while hooking up equipment, 5 minutes or so, then get back on and rev it up it belch's a small cloud of bluish smoke then that dissapears. At first I thought it might be loading up on unburnt diesel fuel, but unburnt diesl fuel is white smoke,, correct?