I got this 96 V6 3.8L Camaro from my dad and it has been sitting up since 2001, and yes it runs fine but i looked in the radiator and it's has brown and gunk in it. I've heard getting it flushed eats up seals and crap but I'm looking for the best way to clean out the crap.

 

Take it to a radiator shop and let them boil it out.

 

I didn't know that could be done I'll check the local shops around here tomorrow