Abstract: An apparatus and method for mixing fuel and oil, to achieve a desired mixture ratio, includes calculating a required number of fuel units, to be mixed with a predetermined volume of oil, for achieving the desired mixture ratio, as a function of calculation terms including the desired mixture ratio and an arbitrarily selected correlation number correlating the predetermined volume of oil to the desired mixture ratio. The required number of fuel units is thus calculated without the use of a calculation term equaling the predetermined volume of oil, thereby facilitating accurate mixing of even custom mixture ratios with simple calculations that can be done mentally.

Abstract: A container assembly includes an outer container and at least one inner container whose internal volume has the same ratio to the remaining internal volume of the outer container as the desired ratio of liquids to be mixed. An orifice in the inner container establishes communication between the lower end portions of the two containers so that a previously mixed liquid mixture of a predetermined ratio resides at the same level in both containers. The container assembly may be filled with additional mixture of the same ratio by filling the inner container with one liquid and by flushing that liquid from the inner container and into the outer container with a second liquid until the outer container is full.