Saw this stuff on the Eastwood site the other day, its a paste you apply to the iron exhaust manifolds so they have a dull grey/steel look instead of rust.

http://www.amazon.com/Calyx-Cast-Exh.../dp/B003D0R426

Anybody try it yet? Some reviews mixed on how long it lasts.

 

Have used it, it is durable with good prep and curing. No prep, no resilience.