Abstract: An improved vehicle transmission oil sump filling apparatus and method of using same, wherein the apparatus includes an integrally formed extension on the distal end of an otherwise conventional filler tube extending a predetermined distance into a transmission sump, and a sealed adapter assembly adaptable to being mounted in the entrance of the fill tube. The sealed adapter assembly includes a single short oil supply tube together with a pressurized air supply and sensing tube integrally formed therein. An air pump is operative for continually blowing air through the sensing tube while the transmission sump is being filled from a source of oil by a reversible oil pump. Once overfill of the sump is sensed, the overfill is drawn out under suction by the oil pump until reaching the point where air once again flows through the filler tube, indicating the appropriate sump oil level.