Something that seems to work better at loosening seized/rusty threads than oil is paraffin- - - - -the oldtime sealing wax that's available in big blocks at the canning supply department of most grocery stores, or candle wax. Heat a stuck bolt or nut until it's almost red, and apply the wax liberally. I use chassis grease, beeswax (toilet bowl seal rings) and paraffin to make cast bullet lube, so I always have a couple of boxes of paraffin blocks around the gunsmith shop.
Jerry
