A pump fitted with 50mm bore ball bearings uses oil whose viscosity ranges from 100cSt at cold pump start-up to 7.5Cst when running at maximum speed and load. If these viscosities are the safe limits for the oil, specify the maximum start-up speed and the maximum running speed you would recommend for the pump. A pump fitted with 50mm bore ball bearings uses oil whose viscosity ranges from 100cSt at cold pump start-up to 7.5Cst when running at maximum speed and load. If these viscosities are the safe limits for the oil, specify the maximum start-up speed and the maximum running speed you would recommend for the pump.