Through the venture with my toy hauler project I have used several different things to achieve the goal. I have to tell you about a product I found this weekend that was absolutely amazing. IT is called Motsenbocker's Lift Off
http://liftoffinc.com/products.htmI went looking for more 3M adhesive remover and Home Depot no longers carries it or didn't have it at the time. So I gave this stuff a shot and I have been very impressed. It is no where asagressive as the 3M and worked very well at removing adhesive and grease.