That's what the antique car guys use to unseize an engine that's been sitting for decades. I find that Liquid Wrench works faster for things like rusted bolts though.

As an aside: I have been using tranny fluid (leftover stuff) mixed with the dregs of 5W30 containers as my go-to quick lube. It soaks in very quickly and then stays tenaciously. Great stuff.

I guess a little homebrew penetrating oil could make it easier to get some of the small bolts loose on an abandoned car. It still takes a lot of torque to get them off though.