I put 1 qt of 2 cycle oil in a 3 gal portable gas tank. I also add Startron fuel additive.I fill the container with 2-1/2 gals of high test. I disconnect the main fuel tank line just before the fuel pump. I hook-up the portable tank to the fuel pump intake side, start the engines, and let it almost empty the tank. Been doing it for 8 years and never had a problem.