I just use MMO and/or Stabil in all the gas that have for my small engines. The only one I ever had issues with was the Allis Chalmers 620 but it sat for over ten years. The B&S on my MTD rear tine tiller that I bought new in the early 1990's is the best starting engine I own. Full choke and it starts on the first pull in late May after setting since September the prior year. I rarely use the full tank of gas over the course of the summer so the mixture that's in the tank likely has gas that several years old.