I own a 2012 series Troy Bilt Pony Model 13WN77KS011. This year before changing my oil, I read somewhere on the internet, that the best type of oil for my mower was 15W50. So, I went to Autozone but they didn't have any 15W50, so I thought I would get the next best thing, which was 20W50. I thought since the numbers 15W50 and 20W50 were close numbers to each other, it would be okay to put in 20W50. So, I put in 2 quarts of 20W50 (as the owners manual said to do). I didn't think it necessary to have to read the dipstick to see if there was going to be enough oil. So, I went ahead and started mowing with it. This is for residential use only, not commercial use. I cut my grass about once a week and it takes me about 20-30 mins to finish cutting my grass. The temperature where I live, recently has been running between 80-95 degrees past few weeks. Since, I put the 20W50 in my mower- I ran the mower about 3 times with no problem. However, (yesterday) the 4th time I ran it just as I was about to finish, all of a sudden it started blowing out HEAVY BLACK SMOKE! I stopped it, examined mower for oil leaks, etc. no leaks but when checking dipstick it appeared that the oil level was ABOVE THE LINE (meaning too much oil), so I emptied it out. Did some research on the internet, that is when I found out that my model number takes ONLY 44 OUNCES OF OIL, NOT 48 OUNCES OF OIL. My concern is whether or not, I have done any damage to the engine IF THE PROBLEM WAS EITHER CAUSED BY TOO MUCH OIL OR WRONG OIL TYPE??? I'm no expert with Riding Mowers. Feel free to give me your thoughts, suggestions, advice. Thanks.