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.Ultra-Pure Light Bearing Oil is also excellent for piston valves that are worn or missing plating. The thicker oil will fill the gap between the piston and the casing, and the valves will seal much better than with our regular valve oil. It also works great on the 1st and 3rd valve slides of trumpets or cornets if you like them to slide quickly and easily. Use this oil to prevent stuck valves on instruments that are placed in storage for several months.Synthetic, odourless, long-lasting.