Yamaha - Oil Tank Engine Lubrication System 6H3-21707-06-00. Overview. Oil delivery is something you don't want to second guess, especially on a two-stroke setup. I've seen cracked or aging tanks cause air leaks and inconsistent oil flow, and that's where bigger problems start. This is one of those parts you replace to eliminate risk and keep things simple. When it's right, you don't think about it-you just run the motor and trust it's getting what it needs.. Key Features. Integrated Oil Storage