Has anyone used the Ethos- Fuel Re formulator. Everyone that has used this or sells it claims that it is a life saver, getting 3-5 MPG better? It is a formula of specially designed esters, you put into your oil, and your gas. I bought one bottle at $40 bucks....very expensive...but it did seem to work. My truck gets 10mpg in the city, about 8.5-9 in winter with the crap they put gas in winter. I used this stuff back in January when it was still below 35 most every day. What is hard for me to tell, is I used it in the oil (half the bottle), and two tanks of gas, but I drove a ton of hwy miles immediately after. It seemed as i was getting 15mpg according to the control panel, but I dont believe it. I want to know what other luck other people have had before I spend so much more on this stuff.