A roller cone rock bit (10) is provided that has a sealing system with double elastomer seals. A first elastomer seal (30) is disposed between a cone (18) having a cavity (24) and a spindle (16). A second elastomer seal (32) is disposed between cone (18) and spindle (16) forming a seal-gap (33). A main lubricant reservoir (49) has a diaphragm (56) disposed between an inner chamber (53) and an outer chamber (60). Inner chamber (53) is in fluid communication with cavity (24), and outer chamber (60) is in fluid communication with external fluids. Cavity (24) and inner chamber (50) are substantially filled with a first lubricant forming a first volume of lubricant. Diaphragm (56) is operable to transmit a pressure of the external fluids to the first volume of lubricant. A seal-gap lubricant reservoir (70) has a diaphragm (78) disposed between an inner chamber (75) and an outer chamber (82). Inner chamber (75) is in fluid communication with seal-gap (33), and outer chamber (82) is in fluid communication with the external fluids. Seal-gap (33) and inner chamber (75) are substantially filled with a second lubricant forming a second volume of lubricant. Diaphragm (78) is operable to transmit the pressure of the external fluids to the second volume of lubricant.