I use some rather old fuel to test the 582 engine on the Chinook+2. This video shows how I went about it. Plane tied to a distant fence post. A temporary fuel tank is used, as the main tanks are in the wings.
Used this opportunity to test electrical output to be sure battery is charging correctly. Engine has 25 hours on it since I replaced a front bearing on the crankshaft and installed new piston rings. See previous videos.