I am kinda obsessive about trying to increase gas mileage on my 98 Sily 1500 with 5.7L. I normally check the gas mileage with every tank by re-setting the trip meter and then calculating mileage upon refilling tank.
I have tried many things to boost mileage but nothing has helped much. Even with a good tune-up, new wires, plugs, proper air in tires, etc; I was only getting right about 15 mpg on highway.
I am a totally skeptical buyer, but I decided to try Zmax. I have already tried other so-called friction reducers with no luck, so I did not expect anything to happen with the Zmax. However, the Zmax offers a money back guarantee if your mileage does not increase, so that's what put me over the edge.
Anyway, I changed the engine oil and added the Zmax treatment. I was completely shocked to see my highway mileage go to over 18 mpg, representing a 20% boost in mileage. I have now run about 4 tanks of highway gas just to confirm this.
So far, this is the ONLY thing that has given me a substantial mileage boost. Has anyone else tried Zmax??
