I again tried the lemon, vinegar, salt combo on some old wrenches and it worked very well. I had a bunch of very old year wrenches of all makes and styles up to 2" being 20" long and the soak worked very well. Some of them are really weird, and super old, and they really cleaned up nicely.

I'm going to try this solution in my heated ultrasonic to see what it does on really bad stuff. Easier than bead blasting, and cheaper than anything else.

Good tip, that's why I'm bumping it again, thanks OP.