Ultra-Pure Light Bearing Oil is used to oil the rotating bearings on the top and bottom of rotary valves. It is thicker than Ultra-Pure Professional Valve Oil and is just the right weight to lubricate the bearings. If your bearings are older or worn, then use Ultra-Pure Linkage, Lever & Key oil. USAGE INFO Place a few drops on the rotating spindle bearing under the cap and also on the bottom side of the rotor valve, where there is a small gap to place oil