I tried Kerosene last night, granted it was a old jug (which I don't know if it has anything to do with it) but it didn't take them off, maybe helped a little. I didn't sit it there for a while, should I hold a rag on it for a longer time I did about a minute?
I also used lacquer thinner, that seemed to work about as well as the kerosene but didn't remove them.
I was thinking about getting some Trix by Carpros but I don't see a point in buying any other tar removers as I dont see anything being much better than Kerosene or thinner...