The present invention relates to an oil filtration system for off-line filtering of contaminated oil from diesel machinery (1), the oil filtration system comprising a system inlet (4) for receiving an inlet flow of contaminated oil from the diesel machinery (1), a system outlet (5) for releasing an outlet flow of filtered oil to the diesel machinery (1), an oil filtration unit which is in fluid communication with the system inlet (4) and the system outlet (5), the oil filtration unit comprising an oil filter (6) which is adapted to receive the contaminated oil and to release the filtered oil, a pumping unit (7) which is arranged upstream of the oil filtration unit, the pumping unit (7) being adapted to provide a flow of contaminated oil in a direction from the system inlet (4) to the oil filtration unit, a temperature sensor (13) for measuring an oil temperature, the temperature sensor (13) comprising a signal transmitter adapted to transmit a first electrical signal reflecting the measured oil temperature, and a control unit (14) adapted to receive the first electrical signal, to compare the measured oil temperature with at least one reference temperature, and to adjust the pumping flow rate of the pumping unit (7) according to the comparison of the measured oil temperature and the at least one reference temperature, where the temperature sensor (13) is positioned upstream from the oil filter (6) in order to measure the oil temperature of the contaminated oil immediately before it is received by the oil filter (6). The invention further relates to a method for off-line filtering of contaminated oil from diesel machinery (1).