I use the PowerService (silver bottle) and I would say I average 1 to 1.5 MPG better with it. I do have a lot of variables on my daily drives, but I also hand calculate the MPG and document every fillup in an Excel Spreadsheet so I'm not just shooting from the hip here.

I was hesitant to run any additive with the 6.7, but I got a personal email from the good folks at PowerService that explained in detail why they're product would work for the 6.7 and why it won't void a warranty as some think.

Guys, please don't flame me for using "snake oil" as some people call this stuff. It's a choice we can make and for me, it's simple, I see results.

I wish I got paid (or at least a product discount) for endorsements...