What happens when you run a lawn mower without oil?
You will burn the motor up, which will be a very costly repair.
On my Craftsman Lawn Mower, I have to raise the lawn mower or tilt it on it's side, and underneath where the blade is, there is a large drain plug. Take it off and catch the oil. This is a great time to clean the underside of your lawn mower and either sharpen or replace your blade.....Nothing cuts better than a sharp blade!
Craftsman 6.5hp lawn mowers can use two kinds of oil--"HD 30" oil, which is a single-weight SAE 30, or the same oil you put in your car. (If you have a Honda lawn mower, you have to run multigrade oil in it.) I always have a case of 5W30 Castrol sitting there, and that's what I use because it's right there already. I also have some 15W40 Rotella on hand, but I wouldn't put that…