Instead of thinner, I would suggest a compound polish / cutting cream setup, or a good scratch remover.
Playing with the thinner on car's paint can be dangerous.
1st, the scratches may be cleaned with plain water and a piece of cloth or towel. Then, compound polish / cutting cream may be carefully applied to dilute or remove the scratches altogether. If scratches are not deep and go OFF, then no need to do anything else, however, if they are deep, then "Qalm" work with matching paint may be reqd.
If they are extremely deep, then none of the above might prove effective, and proper paint work might be reqd.