Reply #19: I haven't been keeping exact track of my mileage recently, [View All]

[necso]

but years ago (I used to always fill up and calculate mileage*) when they changed the formulation, my mileage went down like 10-15%. Oddly, the additive in question was supposed to decrease pollution, as I remember it.

I asked around at that time, and some other drivers had made the same observation. But it seemed to vary by vehicle, and maybe driver.

*: By doing so, I was able to identify gas stations where a fill-up seemed rather large for the miles traveled, and I have avoided these since.