I was looking at lots of pictures of the different cars raced at the league races. I noticed quite a few look like they have a teflon washer on the dfw, it also looked like one was on the rear also. Are these glued to the body or are they just free spinning. Is this for oil and graphite or just oil cars? Is there an advantage to running them on the rear also? I have seen posts about using clear nail polish instead of the teflon, same questions on that also. Also with the nail polsih is that just painted on the bare wood or can it go over the paint. Just looking at things to do, our district race got moved from March 2nd to march 23rd so that gives me a few more weeks or messing around with the cars.