Rev. Rul. 68-327

In some instances gasoline is sold by the producers thereof on the basis of actual volumetric gallons. That is, no adjustment of actual gallonage is made for variations in temperature. In other instances producers sell gasoline on the basis of actual gallonage adjusted to equivalent gallonage at 60 degrees Fahrenheit. Held, in computing the manufacturers excise tax imposed by section 4081 of the Internal Revenue Code of 1954 on sales of gasoline by producers or importers thereof, tax liability is to be measured by the number of gallons invoiced to the purchaser, whether they be actual volumetric gallons or gallons computed on the basis of a temperature adjustment.