50/50 acetone and brake fluid. I made a litre or so of this stuff up last year and it's been incredible on everything from seized caliper slide pins to tractor double-wheel nuts. If you can't use heat, use this :thumb2
for ali corrosion cellulose thinners works well, if you can get it, not tried acetone as to my mind evaporates far too quick, but like the idea of mixing it with brake fluid, but needs to be kept in an air tight container, I bought 25 ltr acetone last year but because the lid did not fit properly, although it was tight, I lost two thirds of it to evaporation, Rick
Bearing in mind how flammable and poisonous Acetone is not to mention it damaging any seals it comes into contact with have you tried using Diesel Fuel ?
When I lived with my parents back in the 1960's we would drain some heating oil out of the tap on the central heating tank it seemed very good until Red and Blue Plus Gas came onto the market.