Yes need pressure tank/closed system. Great stuff. The coupling to the motor is harder to get than the tanks. I have lots of tanks in both 4 and 6 gallon, but no extra ends/couplings. I mix 50:1 but only use Amsoil Saber, or 100:1 pre mix and that of course is with ethanol free fuel. I have been running this ratio in the pre 1965 Johnson/Evinrudes for 40 years now. This information is based on extensive experience in very remote locations NW Ontario. Every repair I do, as well as used outboard sales.....gets a free bottle of Amsoil with instructions. Why? I never want to see them for another repair because of improper lubrication. Too much oil is a carbon creator and fouls plugs as well as makes these old engineering Marvel's appear like crap.....smoking across the lake or river. If every 2 stroke outboard was run as I have recommended......they would not be illegal in states like California.