Circulating oil “M” are used in circulation systems for plain bearing lubrication, either as an oil bath or oil mist, as well as for lubrication of toothed transmissions not requiring application of oils with anti-wear and EP properties. Lower circulating oil viscosity grades are designed for lubrication of high speed spindles, precision grinders and textile industry spindles. Higher oil viscosity grades are used for lubrication of steam engine cylinders, as well as in circulating systems of medium-loaded toothed transmissions and bearings operating at medium-elevated temperatures, where application of oils with EP properties is not required.