Breathing new life into the 318 in the Scamp!

If you are shooting oil based paint, in cold weather just use acetone, it will flash quick enough, if the opposite extreme, if it is real hot out use mineral spiriits, it dries even slower than laquer thinner.
There are actually two different types of rustolum, the one you shown, and they also make one that says "industrial".
The "industrial" stuff I have found to be much more durable but it is a couple more dollars for a quart.