I typically start with a lot of swearing. Once I've calmed down I spray with Kroil and let it soak, then bump them with my battery impact driver. If that doesn't work, I head for the fridge.

Yes.

I've gone the other way on the thermal front on parts I didn't want to heat up because of possible heat treatment issues or proximity (as in this case) to something delicate..

I've used both dry ice baths and liquid nitrogen over night in conjunction with the acetone/ATF mix.

S/F,FOG

WRT acetone/ATF. Does it actually creep horizontally?

It appears to creep horizontally, I have no hard data. I try to arrange for a vertical application. The best application is old mil-surplus barrels. Some I have to do a relief cut on the shoulder, freeze, then submerge in a 6" tank for a day - week. Some of those threads are on so tight that you can crack the receiver if you don't take any precautions.

S.F, FOG