The Optimus had a built-in cleaning needle that worked when you turned the fuel control all the way open.
I used Amoco (remember them?) lead-free, white gas in the stove. It worked just fine.
I stopped at an Amoco station, handed the Aluminum, 1 Quart, fuel bottle to the attendant and told him to "Fill it up", (now this is really going to date me!), it cost $0.24 CENTS, to fill. I gave him a quarter and told him to "keep the change!"