I'm new here as well. The only thing I've found that improved my mileage was to switch to Redline oil. I researched it well and was still skeptical. Then I drove from Chicago to Baltimore and saw real gains of almost 10%. One thing though, use a high capacity oil filter. Do your research. I used a Bosch the first time and was a bit unsatisfied. I now use Microgreen. When I change the oil again I'll let ya know. Cheers!