Have found one of my old bottles of AutoGlym Super Resin Polish and its pretty old (5+years)
Can it have gone off? Or do damage if applied to bodywork?
Should be okay. If it’s a liquid polish give the bottle a good shake to make sure the wax and the carrier hasn’t separated.
If it’s only 5+ yrs old, I’d say you’re polishing your car too often… 
As said…It will probably be ok
But why save it?
I would throw it away and buy another if you want to use AGSRP
The formula has changed and now has less white powder residue
BTW…There is no wax in it…Its a very weak sealant and swirl filler with slight abrasive properties
I havent used it for years…There are many better products out there
Yes - I had the same issue - bought a big 1L bottle from Halfords - nice and creamy - went to use it a few months later - like water ! I emailed Autoglym who asked me to return it, they emailed back saying it has gone watery and was out of spec (!) and sent me a new bottle … and 2 air fresheners for my trouble. I used the new bottle at the weekend - its also gone thinner than it was … 
yep, same here, it appears to degrade somehow and goes all watery after a while, shaking doesn’t help. As said above go buy something better, I only use as still got some in garage (waste not want not), but only use now on old car not on the shiny 5.
Yes it does go off. Sometimes can be revived by a good shake up but at 5years old I’d bin it.