I can't comment on a fuel additive of unknown age or brand. I was never much for fuel additives until recently. I'd read so much about ethanol gumming up carbs and such that I decided to buy some Sea Foam and try it in my Mustang which only gets driven maybe twice a month if that, and also in my lawn machines (two mowers, trimmer, edger, blower). I never run a full tank of gas through my trimmer, etc., so I can't guage any improvement in effficiency with them, but I do in the mowers. I mixed some in my pushmower the last time I mowed. It usually runs through a full tank (approx. 1 quart) doing the front yard and about an eighth of the back yard. I wanted to run the full tank through it to get the most out of the Sea Foam and it just kept going. I ended up cutting my front yard and about two thirds of the back yard on that tank. That's about 6000 sq. feet more than before, which is about 150% increase, and it seemed to run better also. So, if for no other reason, I'm sold on Sea Foam for the increased fuel efficiency.