SO THANKFUL for Amazon reviewers!! I bought this item (small bottle from Wally Mart) based solely on Amazon reviews I deemed trustworthy. I've only used in push lawn mowers behind a never ending saga of despair regarding (several - far too many - mowers) since moving to New England. No gas stabilizer, winterizing, storage concerns are needed where I'm from. Mowers never get "stored" in the south... Sta-Bil first used in a 7.0HP Craftsman (take no prisoners) mower. I'd been religiously adding Seafoam Gas Stabilizer with every tank full of gas per first owner's recommendation, but mower started to choke within a year. I'd been religiously changing oil and filters, as well as adding the gas stabilizer since ownership. Sta-bil was a literal, immediate "shot in the arm" for the mower's performance. I bought this large bottle from Amazon (cheaper than Wally) for my 'new', very expensive Toro mower, also purchased used (from big box store). The oil, air filter, and blade were pristine, so I assumed caurberator and gas filter had been maintained as well. I still experienced what I sensed was some sort of hesitation (blockage) in cranking and performance. I'd been adding Seafoam to each gas fill per the advice given from Craftsman owner. I added Sta-Bil to Toro the day it arrived from Amazon.... Wow. What a difference. Immediate. Paid a nail biting price for the used mower. Beat myself up behind the decision until adding Sta-Bil. It literally made the purchase 500% worthwhile. Can only thank previous posters, and wish future buyers the same results.

Had an edger wouldn't start. Poured an ounce of this in and let it sit a few hours. Came back and it started. My riding mower was surging and while running I put a couple ounces in the tank. After about 10 minutes it stopped surging. Nice that I didn't have to hassle pulling the carbs and cleaning them.

I got this mower curbside. It would hit on starter spray only. Rebuilt carb and mower fired right up but it struggled to get a smooth rpm plus I could hear a low knocking sound also. I thought bad motor no problem I have extra engine to swap it with. I tried Fast fix as a lark. Poured a easy ounce of Fast Fix into a very low level of gas in mower. Clamped the bail to keep it running and walked away for at least 15 mins. Checked back and you could still hear knock and stumbling rpms. Walked away for another 5 minutes and came back to a absolutely smooth running mower and the mysterious knock is gone also. Unbelievable results . This is a electric start mower that should bring me good money.

As my walk behind self-propelled Craftsman mower aged (...now about 10 years old) it began running a little rough. The mowers in good share otherwise and use of this additive has made the engine run very smooth. An simple, no fuss, economic solution to mower replacement.

My Honda had been surging terribly. I tried new fuel and cleaning the pilot jet with carb cleaner but that didn't work. As soon as the auto choke fully opened (quickly in South Texas summer temps), the surging began. My best guess was restricted fuel supply. Thought I'd give this a try before dismantling the carb or even cleaning the fuel filter. Added just a v. small amount to the .25 gallon tank and ran it for 15 mins. Had a big effect and was even better when I started it the next day.
If you're experiencing surging, replace the fuel with new fuel and give this a go. I also plan to add some fuel stabilizer in future and use a smaller fuel container!