I had to remove the decals off a huge 5th wheel trailer once, I tried pressure washer and heat gun and was making very slow progress. Went to an auto detailing and accessory place in town and they hooked me up with some sort of remover, and it worked like a charm. Don't recall the name, but it smelled rather citrus like. Sped up the process immensely, might be worth checking around your area and see what the pro's are using.
^^^
Citrus based adhesive removers work exceedingly well at dissolving the adhesive and all the residue. It won't harm the paint either ... at all. Here's what I use.
![[Linked Image]](https://www.cutcat.com/item_images/desolvit.jpg)
The problem with old vinyl decals is they become brittle and are difficult to peel off without tearing. A hair dryer has just enough heat to softer the vinyl so that it can peel off and De-Solv-it applied at the edges where it can attack the adhesive helps but it won't magically lift the decal off. You won't find a chemical solution that will bubble the decal off and not harm the paint.
Removing decals requires a two prong approach. Peel the decal off and then remove the adhesive residue.
![[Linked Image]](https://2.bp.blogspot.com/-pfgMegXmFaA/UKLPsPcgLYI/AAAAAAAAXL8/xhsg0OGCn4U/s1600/Bikini-Car-Wash-Babe-You-Missed-a-Spot.jpg)
![[Linked Image]](http://i22.photobucket.com/albums/b307/cartod/photo3_zps4af90295.jpg)
