Comments about SeaSense SeaSense Oil Mixxing Bottle:
This is the only way to mix oil into your fuel. The bottle has several scales for different oil - gas mix ratios. Includes a screw on cap, and the opening is just small enough that I can flip it upside down and let it rest inside the opening of my tempo fuel tank, so all the oil drains out. The cap keeps any residual oil inside, keeping my boat interior oil free.