I have 2 old mowers that still run well. One is a 1977 Jacobsen with a non-original Briggs and Stratton 3 horse. I was given the mower by someone I know and got it running. It had a throttle problem where it would not hold a speed. It sped up and immediately started to slow down again. After fixing that, I used it to test spark plugs and found that this rusty old one worked best in it. The other one is a Craftsman from the 80's. I call it "old oil burner" because that is exactly what it does. It burns oil, mostly when first started, or when put under heavy load. It has mismatched wheels because they have broken over the years. I use this one the most because the 4.5 horse engine has more power to it than the 3 horse one. Also, a friend of mine has 2 original lawn-boy commercial mowers that still work.