Whenever a rotating assembly is submerged in an oil bath, air bubbles, otherwise known as foam, form on the fluid surface. For example, the crankshaft in engines can create foam in motor oil, while differentials can create foam in gear oil. In motorcycles, shared-sump transmissions, where the transmission and engine use the same oil, are good at creating foam. Foam in hydraulic lifters can create valvetrain noise because the foam is made of air that compresses and creates lash in the valvetrain. Foam can lead to poor component protection and ultimately mechanical damage. That’s why controlling foam is a critical part of lubricant formulation.
See the October AMSOIL Magazine for more information.
