Rust converter: use it on exhaust manifold?

The exhaust manifold get too hot for it to really rust away - plus its thick compared to exhasut pipes. The thin coating ot current curs protects it pretty much from further rusting. The "Extend" type treaters probably would not hurt it but at 200k how much longer you looking to extend its life? I'd let it sit overnight - and it may smell when you get it hot the first time.

========= Put the heat shield back on. Do not coat the exhaust manifold with anything. The exhaust manifold is cast iron - thick enough that surface oxidation (rust) has no effect. However, I have an older (1977) Toyota truck with an earlier heat shield design without slots for venting which caused the exhaust manifold to crack from lack of ability to dissipate heat (so I replaced manifold and added later design slotted heat shield). During operation, the exhaust manifold can glow orange hot - so I would not apply anything extraneous to the surface.

Yea, not a good idea. Thanks, geronimo