A method for manufacturing an oxygenated gasoline-blend by blending a hydrocarbon Basestock for Oxygenate Blending (BOB) with an alcohol such as ethanol to a required octane specification first blends the BOB to an octane number, (RON+MON)/2 based on the octane sensitivity (RON−MON) of the BOB and the proportion of alcohol to be added to the BOB, such that when the BOB is blended with the specification proportion of alcohol to form the oxygenated gasoline blend, this blend will have the required octane specification. The blending of the BOB with the alcohol will typically be done at a location remote from that where the BOB is blended, e.g. at the product distribution terminal after being transported from the refinery by pipeline or tank car.