An oil skimmer for removing oil floating on surfaces of bodies of water. The oil skimmer includes a support frame, respective drive pulley and guide pulleys rotatably mounted to the support frame on respective shafts, and a drive train which rotatively drives the drive pulley and guide pulleys. A skimmer hose in the form of a loop to which oil adhere floats on the body of water and is driven by the drive pulley through the guide pulley onto and off the surface of the body of water carrying adhered oil. A skimmer hose scraper disposed between the drive and guide pulleys removes the oil from the skimmer hose into a collection receptacle. The drive and guide pulleys comprise replaceable, quick changing inner and outer pulley halves that sandwich respective central hubs therebetween to space the pulley halves to fit skimmer hoses of different cross-sectional sizes. The central hubs with attached drive and guide pulley halves are affixed to the drive shafts using a quick release nut which threads to the shafts. A movable safety housing includes a safety system of horizontal and vertical drive pulley safety blocks affixed thereto which press the skimmer hose into frictional engagement with the drive pulley when assembled in an operative position and releases the skimmer hose when in an inoperative position to stop the skimmer hose. The skimmer hose scraper is adjustable to compensate for varying positioning of the skimmer hose.