My Toro is about 12 years old and runs fine but it loses oil. I can see oil with dust & dirt stuck to it around the base of the motor, on the deck and all around the fins of the motor.
I am guessing it needs a gasket ? Since the mower is 12 yrs old does it pay to tear the whole thing apart and how would I determine if and which gasket it is?
Clean the entire deck and then lightly coat the deck with a light powder. Baby, foot, flour etc. Allow it to sit for a couple of days. If no indication of where it is coming from, run the unit for 30 minutes and then let it sit. The powder will show you where the leak starts.