i got 650 gal. of the 500ppm dropped in my tank at home 6 weeks ago when it was 3. 159 a gal. i am glad i got it now. the 500ppm raised my mpg by 2. 5 miles miles. this 15ppm has alot lower btu. that stanadine performance forula raised a customers of mine 2 mpg in a 3rd gen.