ABSTRACT
Gear oils are the unseen workhorses of the automotive lubricants. Lacking the advertising clout and consumer attention that engine oils command, they are the lubricants for the remainder of the automotive power train. The equipment utilizing automotive gear lubricants include manual transmissions, drive axles, power take-offs, and nondrive applications. Other automotive applications using gear lubricants are front steer axles in rear-drive vehicles, trailer axles being pulled or articulated with the drive tractor, power take-off assemblies for transferring engine power to drive auxiliary equipment, and the rear bearing axle assemblies on front-wheel-drive vehicles. The first defining category for the design and formulation of an automotive gear lubricant is the viscosity. The American Petroleum Institute designates service categories for automotive gear oils based on the level of antiwear or Extreme Pressure protection required. Similar to the compatibility properties, synthetic gear lubricants are fully miscible with petroleum-based gear lubes.
