I worked mine over just a couple of weeks ago. I didn’t get the micro-scratches out, but I did dim them. Only when the sun shines at a certain angle on the front can they be seen enough to notice. Ours is 3M, not Diamond Shield, and original to the coach - 12 years. Regular use of anti-UV waxes and protectants apparently has kept it from drying and cracking.
I used old plastic cleaners and polishes by Meguiar’s... the cleaner has a coarser cut, followed by the polish that has a light one. I then researched top polishes for UV protection and found that some I had on hand are not recommended on vinyl or plastic, etc. So I ultimately ordered what 3M says is okay, their expensive Perfect-it Paste Wax, #39526. I’m sure another would be okay as long as it has no warning on it re. use on plastic, but this for sure was. Novus plastic polishes (search Amazon) would work when my old Meguiar’s run out, and likely use newer formulations.
Like with the plastic polishes, I used my Porter-cable polisher and 6” orange Lakeside disk to work the paste wax in... it is strange stuff, hard and wax-like in the can, even tricky to scoop out onto a cloth, but it turns creamy slick when applied. I also did the mirrors since they show signs of blistering chrome that hasn’t peeled yet. I then buffed it all with cotton disk covers. To top it, I used HydroSilex per it’s directions. A lot of work but good enough that I’m certainly not considering film replacement anytime soon.
The main preventative is to thoroughly rinse the film before any polishing. Cleaning gently with Dawn and hot water is advisable to remove bugs and grit to minimize micro-scratches.
Joel
Note the headlamps have film on them also, by Force Graphics in Bend, across Boyd Acres from BCS.