Start with a clay bar kit. If that doesn't work, try a 50/50 mix of thinner and water. If that doesn't work, try wetsanding with 1500, but and polish. If that doesn't work, try repainting the car.
I use Kit brand Scratch Out, it works really good for buffing out plastic headlight and tail light lens, Depending on how bad you can mix it with another liquid polish make it less abrasive. I use it to buff out scratches on my cars.
I'd try whatever weaselpiss compound first. Also, I know it might sound insaine, but a razor blade might work too. With the razorblade, you have to hold your mouth just right, kinda like holding your adams apple just right while it flirts with a straight razor.
Wheaselpiss compound is special order item from Maryland. Contact Merv or bigbird for these special items with high mark-up.
I would start off like John says, with claybar. But if this is Urethane paint it has more than likely stuck down on your finish. That brings you to the next step of color sanding the car. Start with 1500 to 2000 grit wet/dry paper with a hard backing block and flatten the finish. Run it wet with some dish soap (Dawn) for lubrication. Polish it up afterwards with compound. I like Menzerna Intensive Polish and then Menzerna final Polish worked with a Porter Cable buffer. 3M glaze will get you there the last little bit when you get bored from the work. Menzerna is as near as you can buy for genuine weaslepiss outside of Maryland. I think that is what you'll need though. Last step would be Zaino polish. That will fill in the minor imperfections and leave the car looking great.
Good advice. Before I went right into sanding I would try the buffer. I would try some aggresive compound first and then some polish to take out the swirls from the rough buff. I've saved a LOT of paint jobs with the buffer.
After seeing what the guy did about the overspray situation at the POCI convention, I feel confident that the clay bar used in conjunction with a good & non-abrasive cleaner-polish and a wheel will make it look like new. They sent a guy from Texas all across the country to address the situatuions for us. Since I had a shop for him to work in, I invited all of our chapter to bring theirs in so he had a good place to work. I saw him do 21 cars, some in better shape than others, but he made then ALL look great. He uses a blue colored clay because it is less invasive. He gets it wet with water, squirts some polish (made by a company called AUTO-MAGIC) on and clays it down. The water and polish provide lubricity. After that he uses the wheel as slow as it'll go and buffs the polish into the paint. Again, this was a National event, and some one from most every state state in the union got some. He may be planning to come to Nashville and if he is, he'll do it for you and you'll be happy. If you are interested I'll PM you his name and number. The company he works with is called Nationwide Overspray out of (I believe) Dallas TX.
Great info here from several good sources. Thanks for the input.
Greg, did he have different approaches for different paint types, or did his technique stay the same? I wonder what it'd do for my original 39-year-old April Gold paint? It still shines like near-new, but needs a skin-deep scrub.
'68 428 HO M3 Monster, 4-on-the-floor! Need I say more?
He used the same stuff on all finishes. He did have a few that required some extra work. My 20 year old lacquer as well as newer urethane finishes. I saw a '58 Hot rod that had fairly fresh House 'O' kolor on it. The guy was scared stiff of the outcome, but he was as happy as he could be. Same guy has a '64 GTO and a new Solstice, both got sprayed and both are very clean and shiney now. He did 2 different 1948's with original paint and they both looked really good. On one of those, he did use a sponge backed 2,000 grit pad made by 3M. Main reason is it had some paint that was flaking on top and he used this method in order to feather edge the rough spots. Don't be afraid of the clay. With most any lubricity at all, it wont tear anything up, and it really does a good job at the deep scrubbing you mentioned. I had used a meguires clay kit on the Volvo when I first got that car and you would be amazed at the results.
If that doen't work Nash, Get me your e-mail and I will foward you a number of the cars he has done per the convention. !!!Actually I tried and found: When you click on what this gives you, then click on the GTO POWER folder, then click on the NationwideOverspray folder. There are many to look at.