Inside the wheelwells are the massive 37.5-gallon oil tanks, and that is for each engine! The tanks are big rubber bladders made by Goodyear, with the logo still visible. The gas tanks were spread throughout the wings in separate self-sealing tanks for a total of 2,780 gallons. In flight, the four engines could easily suck down 50 gallons per hour each, 200 gph total. Not cheap!