[wrndln]

It sound like you are proceeding the way you should. I removed several door window frames on pickup doors. They weren't real tough to remove. I think if you keep soaking the insides of the frame it should loosen up. Are you sure you are getting the oil inside where the metal parts are stuck together? I used a piece of wood on the underside of the top corners and tapped the wood going from side to side. It finally broke loose and I could slide the frame up and out. I suppose the last resort would be to used a torch (very carefully) to break the metal pieces apart. Since the window frames are made of thin sheetmetal, care would need to be taken not to melt the metal.
Rusty Nelson