Interesting how this topic spurs so much conversation. As I said in the first post, I am not going to take a stance either way; I just want to see what it does to my car. I filled up a few days ago and put in 15.3 gallons of Marathon 87 ($42.67) and my trip meter read 313.9 miles. Doing the math gives me 20.5 mpg.

This is on the high end of what I normally get in the spring/summer (19.5-20.5 mpg) with my driving pattern so I am going to say it is probably statistically insignificant. My driving pattern during the test was the same as it has been in the past--20 miles to/from work a day with about 50-100 miles on the weekend. The only atypical thing during the past two weeks is that the air has been very humid as it has rained about every day in May so far.

Being the risk taker I am, I dumped in another 4.5 ounces to test a second tank.

My other observations are that the car does seem to idle smoother/quieter and the cold engine acceleration hesitation that has been there for years seems to have died down a bit (but it has come and gone in the past). My guess is the acetone may be cleaning the injectors as I have used cheap-as-I-can-find 87 for years and rarely have used injector cleaner.

So I guess if I can conclude anything from the first tank, it would be that if your unmodified car is getting way below 19-20 mpg, you may want to try it out (3 oz acetone per 10 gallons) along with any other possible things (replace oxygen sensors, patch exhaust leaks, clean intake manifold). At worse, the 0.234% acetone mixture will eat all your plastic or blow up your car (couldn't resist that jab) and at best you might see an increase in mpg due to some cleaning of the injectors.

On an unrelated note, I found an oil leaking rocker/valve cover bolt low on the cover and swapped it with one higher up. This fixed my last oil leak from doing my rocker/valve cover gaskets and I got to remove the 'car diaper' from the garage floor as I have no other leaks right now

Next to do are the timing belt, water pump, and front seals as I can see a bit of oil seeping out (no drips yet, she knows better than to drip) from the dust seal/gasket around the plastic front covers and a bit of coolant from around the water pump

I will post the results of the second tank in a few weeks.