Best and cheapest is ATF and acetone (trust me). The 32mm nut is rh thread. Even if you only get a fraction of a turn at a time use the biggest weapon you can get in there. NOT Stiltsons - they will crush it. Try a secondhand tool shop maybe???
Good - Fast - Cheap: Pick any two.
E23 735i; E32 735iL (X 2 - 1 Alpine White and 1 Glacier Blue); E34 535i; E38 735iL; R50 Cooper; R55 Cooper Clubman.
E21 318i; E30 318i; E32 735iL; E34 535i; E38 730iL; E53 4.4i