Just to clear some things up. I have a degree in chemistry and a long time ago worked in the paint industry with solvents.
Acetone is what is called a ketone. It has a double bonded oxygen. Along with esters it is a good solvent for many oxygen containing materials. Oxygen tends to be grabby about electrons and pulls them away from the other atoms creating positive and negative parts of the molecule creating what is called polarity.
Lacquer thinners are a blend of ketones, esters, aromatics and maybe alcohols. Aromatics, benzine, toluene, xylene, etc. have a ring structure the electrons are free to move around it. Alcohols have oxygen too, but tend to be too polar to dissolve some things.
The basic rule is that like dissolves like. That also applies to crosslinked material such as rubber that swell rather than dissolves. Octane has no oxygen or ring structure. Thus it is a poor solvent for anything with oxygen or ring structures in it. Add acetone or other oxygen containing materials, and it will dissolve or swell more materials. Expose non polar material to the aromatics, and they will dissolve or swell them. However, the electrons in aromatics can be pulled to one end by polar materials becoming polar and dissolving or swelling them.
Many types of rubber are very non polar and will swell if exposed to gasoline or rubber. Acetone has little effect on such rubber. I used to use it to clean paint resin off gum rubber tubing. It might not even swell brake parts. You can make rubber resist gasoline and oil by adding polar materials, nitrogen, chlorine, sulphate, or silicone. Silicone isn't so polar, more just like nothing else. So you add acetone and lacquer thinner to your gasoline, exactly what happens will depend on how much, what is in the lacquer thinner, and the grades of rubber in your fuel system. Not all lacquer thinners are alike. The stuff you buy at Lowes won't work with automotive lacquers.