Penetrating Oil

[mgdavis]

Plus eleventy for Kroil and patience mixed 3:1. Mechanical agitation to break the bond helps, with the added benefit of providing release for some of the frustration caused by the stuck part.
I've gone as far as placing ice on one side of a thread and taking a torch to the other; that was for an obsolete brass deck fitting that I *really* did not want to bugger up.

[ConstitutionCowboy]

From the title, I thought this was going to be about K-Y jelly. Though I was disappointed, I read on. 

I'll have to give the formula a try next time my nuts and bolt gets rusted in place.

Woody

[ConstitutionCowboy]

https://www.youtube.com/watch?v=xUEob2oAKVs

Don't put too much stock in the acetone/atf mix. I've found that after oiling, time is a big factor. Also hitting it probably helped a lot. One other thing is that when you feel it move, don't keep going, retighten it and loosen it a couple times and it'll loosen the rust without overstressing the bolt.

I've used this method many times. It seems turning the bolt or nut back and forth tends to grind up the rust freeing things up. Sometimes you need to stop along the way and rotate whatever you are trying to remove back and forth some more. Sometimes giving whatever is stuck a good whack(that won't destroy it) while applying force with a wrench is the best way to get it moving. If it is a nut on a rusty stud, sometimes tightening it a little will break it loose. Be careful that you don't shear the stud off, though.

Woody

[kgbsquirrel]

I've used this method many times. It seems turning the bolt or nut back and forth tends to grind up the rust freeing things up. Sometimes you need to stop along the way and rotate whatever you are trying to remove back and forth some more. Sometimes giving whatever is stuck a good whack(that won't destroy it) while applying force with a wrench is the best way to get it moving. If it is a nut on a rusty stud, sometimes tightening it a little will break it loose. Be careful that you don't shear the stud off, though.

Woody

A bit like tapping threads to begin with; back and forth gets the job done.

[MillCreek]

A bit like tapping threads to begin with; back and forth gets the job done.

That's what she said.

[tokugawa]

Every time this subject comes up I have to chime in.

 BE AWARE some solvents and penetrating oils, are VERY dangerous when heated, just like brake cleaner.  Best to use the heat first.
 

[ConstitutionCowboy]

That's what she said.

OH! You knew her too, eh?

Woody