Dried on cosmoline stain.

[jak]

If you look at the ingredients of nail polish remover it is acetone or ethyl acetate and isopropyl alcohol, the same solvents you would use to remove cosmolline.
It's a great marketing scheme to make women pay the same price for a tiny fancy 2 oz bottle of acetone as men do for a quart of acetone in a hardware store.

[Mike Muzzarelli]

My latest m1 acquisition had cosmoline stains all over the metal that looked like rust stains.
For lack of a solvent at hand I grabbed the supreme commanders nail polish remover and some four ought steel wool and rubbed lightly and the stains came right off the parkeriing underneath was perfect. Just thought I would pass it along just put the bottle back.