More than 30 military grease specifications are a measure of the many and special demands made on lubricating greases in the Armed Forces. Broad temperature range greases, which require synthetic fluids and nonsoap thickeners, represent the newer specifications. One of these specifies a grease to lubricate ball and roller bearings from −65 F to +450 F. The effect of humidity on the shear stability of a modified bentonite grease is shown. Research problems involved in reaching goals of −65 F to +900 F for lightly loaded bearings and −40 F to 600 F for E.P. applications are discussed.