I use lucas oil sabilizer and fuel treatment in all of my vehicles and I have increased fuel mileage in all of them. the lumina went from 23 mpg to 27 mpg. Semi-tractors are known to get 5 mpg I averaged 7.25 mpg in the mountains and 8.25 mpg on flat land runs. The 98 Freightliner has 1.1 million miles on it and lucas really helps out and you can tell by the mileage I get. This product really works!!!