A 50:50 mixture of the above mixture is the best thing I have found for frring up metal parts that are "locked-up" by time and rust.
It is very volatile and the acetone evaporates away preety quickly so you have to keep it sealed up and brush on the amount you need.
I had a flywheel on a Briggs and Stratton engine I couldn't get off until I let this mixture work for about a week.
I found out about this mixture from an internet forum.
