Filling over old filler

[68BirdinOz]

I'm fixing up a few small rust spots (will use adhesive to glue in panels instead of welding) and dents. I don't want to have to go to bare metal everywhere, but want to know if there are any potential issues if I just fill the repaired spots and work in the new filler up to the old. Original filler was applied 20+ years old. I'm not after great paint, just a 20 footer.
Thanks

[renegade6]

I would remove all that you can. Nothing else will piss you off more after you think you have it right, paint over it and then a bubble shows up or, it doesn't adhere. I know from doing it the wrong way.

[bel_mor]

if your paints under 6 mils thick you can paint over what you have there. as far as filling over body filler that is already there i wouldn't rec-amend it. it will only take a few more minutes to take the filler completely out with a grinder.. besides its good to grind a decent tooth on your metal for your filler to bond too. as far as gluing panels instead of welding them???? never heard of it if you are just doing a quickie use a product called duraglass it works great for stuff like that

[mcraw66chevy]

i personally spend everyday taking out old filler from muscle cars . take it out it only takes a few min . the filler we had 5-10 years ago is nothing compaired to what we have today use self etching its a bit more but well worth the money spent . its usually blue or yellow , trash the old pink bondo it junk . i own a body shop and would use nothing but evercoat personally but thats my choice . got in one of the slickest nicest 1969 camaros that ive ever seen and today it maks the customer sick to see what i had to do . he spent 50 g on this car last week im an inch into body filler now . so do the good stuff its worth it .

[68BirdinOz]

Thanks guys. I will remove it all. It means the whole car. Bugger. Seems to have a very very thin coat over every panel......