I recently bought a 2002 ram 2500 5.9 magnum and exhaust manifolds are really rusty should I change them or bring it to the dealer?

 

Dealer will charge you an arm and a leg.

 

If they're not leaking I wouldn't worry with em

 

Most likely its just surface rust . It should last a while unless there leaking

 

Cast iron manifolds basically never wear out on gas engines......

 

...And will rust because of moisture in the air, expecially when they are hot.

 

+1 unless they're coated they all have some rust almost instantly.

 

put a coat of bbq paint on them

 

i would have to disagree with this. i tried bbq paint and it was gone in less than 6 month and i took all day to clean and sand blast my manifolds before paint. i think if you are going to try painting them you need to use an engine enamel with ceramic.

 

I used the vht 2000* flameproof paint on a set of headers. Didn't last long - maybe a few months.