The differential of a vehicle serves as a gearbox which lets each wheel rotate at different speeds. There are several moving gears which make up a differential. Like in an engine, all these moving parts need to be lubricated in order to run smoothly. That is why differentials require a lubricating oil solution to keep its components running smoothly and properly.
Without differential oil, the components of the differential mechanism would get damaged and malfunction. But you can’t just use any type of oil to lubricate your differential gears. The oil must be specifically made for these gears, which is why differential oil is sometimes referred to as gear oil.
You might say it is motor oil, but it is different than standard engine oil. Differential oil is specially formulated for the differential gears of a truck, SUV, or car. From a scientific standpoint, differential oil is thicker than engine oil. Whenever you have a higher viscosity oil, the inner workings of the components do not get lubricated. Only the outer areas of the components.
In this case, the differential oil will merely stick to the outside of the gears like a coat of paint. It will not penetrate through them.
Types of Differentials oils
There is no just one type of differential oil. Like every type of oil, there are multiple versions of it based on how they’re formulated. The American Petroleum Institute has divided differential oils into different classifications. Each classification is based on a rating for the oil. This is not the same rating that engine oil has, so don’t base your differential oil on the engine oil rating.
Since differential oils are thicker oils, you should never put them in an engine. On the flip side, engine oils are too thin to lubricate heavy differential gears properly. That is why you don’t use engine oils for lubricating differentials. Keep the two separated and only use them for their respective components and systems.
The ratings of differential oils range from GL-1 to GL-6. The “GL” is an acronym for “gear lube.” The number of the rating relates to the operation condition and additives in the fluid. If there is a lot of metal-to-metal friction taking place between each of the gears of the differential, then you’d want a higher GL rating.
For example, the standard differential oil is GL-1. This oil is suitable for all your basic operating conditions which don’t involve a lot of abuse or shock. But as you get to the heavier operating conditions where intense shocks are common, then you’ll want something like a GL-5 or GL-6 differential oil.
If you are unsure of which differential oil to use for your vehicle’s differential, simply check the owner’s manual of your vehicle and it should tell you. Either that or go to your local auto shop and let the mechanic worry about it. They can change your differential oil and know which oil rating to use for your differential.
When to Change Differential Oil
You must change your differential oil at regular intervals just like any other oil in your vehicle, such as engine oil. However, the length of the intervals is different amongst each of the oils.
When it comes to differential oil, most vehicle manufacturers will recommend that you change the oil at least every 60,000 miles, but preferably every 30,000 miles. It is a lot more difficult for differential oil to be changed than it is for engine oil to be changed.
Fortunately, you don’t need to change your differential oil every 5,000 miles as you do with your engine oil. So, you should only experience having to get this messy job done about once or twice throughout the time you own your vehicle.