I've used it for years because I like the manufacturer and their oils, which I notice do help my transmissions shift smoother, so I trust that their fuel system additive does work.
One bottle usually lasts me a good 3,000 miles of small maintenance doses every tank or two. I add a dash of it per fill up (1/6th bottle or so) just for the heck of it. I figure a bit more cleaning additives added into the mix of Premium Shell fuel should be enough to keep things clean.
"Italian Tune Ups" every day also help build up cylinder pressure and temps to burn off whatever carbon manages to stick on in my Econo motor.
One bottle usually lasts me a good 3,000 miles of small maintenance doses every tank or two. I add a dash of it per fill up (1/6th bottle or so) just for the heck of it. I figure a bit more cleaning additives added into the mix of Premium Shell fuel should be enough to keep things clean.
"Italian Tune Ups" every day also help build up cylinder pressure and temps to burn off whatever carbon manages to stick on in my Econo motor.