The Pfeiffer Turbo rotor runs in two high-precision ball bearings with wick lubrication. The wicks are impregnated with oil eliminating the need for an oil pump and oil flow monitor. The lubricant reservoir should be replaced at least every three years. Where extreme operating conditions or unclean processes are involved, the replacement should occur more frequently. See p.25-26 of the pdf download below for detailed instructions on servicing wicks in Pfeiffer 330 and 510 pumps.