I've got a 13 year old MTD riding lawn mower. It has a 12hp Briggs and Stratton engine. It ran fine one day and the next day it blew fire out of the muffler, (I didn't witness that with my own eyes) it has oil in the muffler and the last time I tried to start it, it spewed a lot of oil out of the air intake. Do you have any ideas as to what could cause this? I was suspecting the rings and I've taken the cylinder out. What am I looking for at this point? Upon visual inspection, I'm not seeing anything that catches my eye. Is a visual inspection enough to determine if the rings are bad? I was expecting to find something obvious since it went from working fine one day to broke the next. Maybe it's not the rings. Any other ideas or suggestions? Thanks for the help.
Dale