Removing oxidized finish from aluminum engine blocks? Also steel fasteners
 

Later this summer I'm doing an engine swap in one of my other cars - original engine is fine but needs rod bearings, which I'd rather do on a stand than on my back (I tried it in-car, ran out of time and decided I'd rather not and just buttoned it back up) Picked up a spare (with extra performance goodies) from a friend that I will drop in in the meantime. This engine came out of a Wisconsin car, so it is not pretty on the outside.

First thing I'm going to do is give it lots of degreaser and a wash, of course. I will probably take the intake off for convenience. I'm going to do easy stuff like replace any dried-out rubber lines, etc. Engine compartment will also get a thorough cleaning, new PS line, steering rack boots, etc.

Due to its northern history, there is oxidation on the surface of the block. I'd like to make the engine look nice before I put it back in the car, but I have no idea what the gentlest method is that will safely remove this oxidation. When it's clean, maybe I'll paint it or maybe just hit it with an appropriate clear.

Also, all the steel bits. This is a driver, not a show car, so I'm not going to take a pile of parts to get CAD-plated. I will soak stuff in my corrosion remover of choice (I'm forgetting the name - comes in a silver jug), but what shall I coat fasteners with afterwards? I don't necessarily need them to look as-new, just nice and not-rusty.

Basically this all concerns a driver-level cosmetic resto of engine bits.

For cast aluminium I have just used thin oil and a scrub brush, depends how oxidized it is.

Mind as well powder coat.
It's an engine. Just takes one seal to turn that clean, or painted surface to junk.

Marvel Mystery Oil, a toothbrush and a LOT of time..