D. OIL SYSTEM  -82- The oil system for K-3 thru K-74 includes a 30-gallon  oil storage tank below the deck of the car, and two  14-gallon oil service tanks, one in each engine  na~elle,  and a transfer pump with necessary fittings.  In K-75 and future, the oil storage tank, transfer  pump and fittings are removed and the oil service tanks in  the nacelles are enlarged to the 26-gallon ’size.  The oil is cooled by a radiator which is located in  the nacelle for the K-3 thru K-8 airships, and which is  suspended from the lower outriggers for the K-9 and sub› sequent ships.  The service tanks are equipped with electrical heating  units to heat the oil in cold weather.  The amount of oil in the service tanks is read on two  oil gages located on the mechanic’s panel.  The amount of  oil in the storage tanks is read directly on the tank  through a trap door in the deck of the car. 