What is Differential Fluid?
RWD or Rear-Wheel-Drive cars have some sort of gearbox connecting the car’s two axles. This gearbox is responsible for the conversion of engine power and its transmission to the tires, allowing them to turn at varying speeds. This part of the car is called the “differential” and lubrication is needed for it to function properly. “Differential Fluid”, also called “Differential Oil” provides the lubrication and cooling of the car’s differential. The fluid is there to protect the gear’s metal surfaces from friction, and to prevent overheating and burning.

Differential Oil is a type of motor oil. It has a thicker consistency though which prevents it from penetrating the innermost parts of the gearbox. It is put inside for its lubricating purpose and works by “coating” the gears. Not as popular as the usual engine oils like brake fluids and power steering pump fluids, differential fluid is also very important and must be changed regularly. Levels must also be checked to maximize the lubricating effects of differential oil. One must check with his/her own car dealer or manufacturer for the proper levels and oil replacement schedules.

There are various types of differential oil according to the American Petroleum Institute. Usually, oils are grouped according to its rating. A GL-1 rating for example is specifically designed for light operating conditions, while a GL-6 rating is for conditions requiring extreme shock absorption like in off-road conditions.

Care must be taken also not to interchange the use of your standard engine oil and differential oil, as these are meant for different purposes. It is also important to stick to regular car maintenance, as changing differential fluids are commonly overlooked. Car dealers and manufacturers also recommend using the differential fluid suited for your own vehicle’s specifications. Internal gears may be damaged if the wrong fluid is used and this will certainly lead to a much costly repair job.