Here's a little trick that will tell you if you need to claybar your car. After you've washed / cleaned your car run your hand over the finish and see how it feels....is it smooth to the touch:headscratch:. If you think it is do it again but this time put put a ziplock baggie (or any other type of plastic sandwich bag). Does it still feel smooth to the touch :headscratch:.....probably not. The baggie makes your touch much more sensitive and detects imperfections in the surface of your car.
Now claybar a small area and try the baggie touch again...it should now feel like glass.
Remember to use a good lubricant (detail spray) when you claybar your car and also refold and kneed the claybar often. Also, there are different levels of claybar out there. Unless your car really has issues you can use the lightest level of claybar and it won't hurt your clear coat.
Personally, I use Adams' Polish claybars as they are easier to work with..... Adam's Polishes :bigthumbsup