Sebum lubricates the skin and hair of mammals. Synovial membranes are found in joint capsules, where they contain synovial fluid, which lubricates joints. The mucus component lubricates the walls of the intestine. Crusting is a process that thins and lubricates leather. Many older cars require leaded petrol because the lead lubricates and protects the soft valves. Their secretion lubricates the skin, protecting it from drying out or becoming irritated. Thus, its secretion lubricates the passage of uterus through which ova move. Water often lubricates faults, filling in fractures and jogs. To lighten her labors, she lubricates the area with her bladder water. This lubricates the bearing inside and out. Once there the water lubricates the interface between the ice and the bedrock. Most ice streams have some water at their base, which lubricates the flow.