System for cleaning degraded oil of oil-soluble degradation products, the system (100, 200, 300) comprising - an inlet (101, 201, 301) for receiving an inlet flow (1, 1a, 1b) of degraded oil, - an outlet (102, 202, 302) for discharging an outlet flow (2, 2a, 2b) of cleaned oil, - a filtration branch (103, 203, 303) connecting the inlet and the outlet, the filtration branch comprising a filter (104, 204, 304) arranged so as to pass a filtration flow (3, 3a, 3b) at a filtration flow rate through the filter in a direction from the inlet to the outlet, - a cooler (105, 205, 305) for cooling the degraded oil to a precipitation regime and thermal insulation for keeping the degraded oil at the precipitation temperature for a dwell-time prior to filtration so as to cause degradation products dissolved in the oil to precipitate and to retain the precipitated degradation products in the filter, - a recirculation branch (206, 306) extending from a flow dividing element (207, 307) arranged downstream of the filter to a flow combining element (208, 308) arranged upstream of the filter, wherein the flow dividing element is adapted to divide the filtration flow of oil into the outlet flow and a recirculation flow (6, 6a, 6b), wherein the recirculation branch is adapted to pass the recirculation flow in a direction from the flow dividing element to the flow combining element, and wherein the flow combining element is adapted to combine the inlet flow with the recirculation flow and to pass the combined flow as filtration flow to the filter for filtration, wherein the recirculation branch (206, 306) comprises pumping means - characterised in that, the system comprises pre-cooling means (210, 310, 311) for pre-cooling the oil received at the inlet. - an inlet (101, 201, 301) for receiving an inlet flow (1, 1a, 1b) of degraded oil, - an outlet (102, 202, 302) for discharging an outlet flow (2, 2a, 2b) of cleaned oil, - a filtration branch (103, 203, 303) connecting the inlet and the outlet, the filtration branch comprising a filter (104, 204, 304) arranged so as to pass a filtration flow (3, 3a, 3b) at a filtration flow rate through the filter in a direction from the inlet to the outlet, - a cooler (105, 205, 305) for cooling the degraded oil to a precipitation regime and thermal insulation for keeping the degraded oil at the precipitation temperature for a dwell-time prior to filtration so as to cause degradation products dissolved in the oil to precipitate and to retain the precipitated degradation products in the filter, - a recirculation branch (206, 306) extending from a flow dividing element (207, 307) arranged downstream of the filter to a flow combining element (208, 308) arranged upstream of the filter, wherein the flow dividing element is adapted to divide the filtration flow of oil into the outlet flow and a recirculation flow (6, 6a, 6b), wherein the recirculation branch is adapted to pass the recirculation flow in a direction from the flow dividing element to the flow combining element, and wherein the flow combining element is adapted to combine the inlet flow with the recirculation flow and to pass the combined flow as filtration flow to the filter for filtration, wherein the recirculation branch (206, 306) comprises pumping means - characterised in that, the system comprises pre-cooling means (210, 310, 311) for pre-cooling the oil received at the inlet.