I've been using 40ml per 40litres of Doozal in my 200tdi Landy, and it DOE'S make a positive difference to the running of your engine. Quieter, smoother, and just generally a nicer drive - not so sure about increased MPG, maybe a mile or two for me.
You can get acetone from :
http://www.seabase.eu/onlineshop.asp?cat=Chemicals|Acetone_(pure)&sbtag=462libcategories
Get yourself a big syringe to squirt it into your tank before you fill up.
At that concentration, I really can't see it doing to much harm to your rubber bits.
Your basically just adding enough the break up the surface tension of the dooozal, and allowing it to vaporize better in the combustion chambers. Too much and it can have negative effects!!