This was easy, because although the bike has a gas guage, I always set the tripmeter to zero when I fill up, so tracking mileage will be simple. Yes, always. I don't trust the guage that much, and I'm used to watching miles after filling up.
My original idea was to run this tank as close to empty as possible, to make sure that all the Microlon put into the gas went through without being overly diluted. Also, since it's a solid that might settle a bit I set the tank on 'reserve' until I got to well below half a tank. If you're not familiar with this, every bike I've ever been around has a valve where the gas line attaches to the tank, and the tank has three positions: off, run or normal, and reserve. Run feeds from a small pipe that sticks up a ways above the bottom of the tank; reserve from a pipe much closer to the bottom. The idea is that with the valve on 'normal', if you run so low that the engine dies you can switch to 'reserve' and have, depending on the bike, anywhere from 10-20 miles to get to a station. I trust that, because unlike the guage it's a simple mechanical device with no gremlins waiting to dance on your nose as you sit by the side of the road.
On this bike, combined city/highway riding has gotten about 120-125 miles before having to go on reserve; once only got 112, but that was on a highway fighting a nasty headwind. So when I hit just over 100 miles I switched the valve to 'normal' and kept going. And hit 120 and kept going. And 125. 130, and kept going.
I got to 147 miles and still hadn't had to go to reserve. At that point I decided to go ahead and gas up because a: it was enough of a difference that it made me wonder if the gremlins had moved to the petcock and I was stuck on reserve, and b: if it hit reserve this morning on the way to work I'd have to take the time to fuel up then. So I filled up to the same point I had before adding the stuff, which took exactly 2.7 gallons. Which works out to 54.a bit mpg, which is about nine per gallon more than before.
I'm a little shocked by that. A couple miles per more I kind of expected, but this seems a bit much. I'm happy, understand, just surprised. And pleased. Of course, this could be largely because of the stuff being in the system; if it continues to give the increased mileage over time, that'll be the proof. So far, it looks good.