How to Change Differential Oil

Lubrication is a vital part of keeping your car running. Car drivers may forget about various oils, such as differential oil, go into their vehicles. Nevertheless, it’s such a crucial part of the system that keeps you safe and moving while on the road. 

Here’s information on how to change differential oil. 

What Is Differential Oil?

A differential oil is an automotive lubricant that keeps your car’s differential operating. The diff is a part of the car’s drivetrain, which moves power from an engine to the wheels. It helps keep all the tires spinning together for movement. The diff is also integral to having the axle shaft have enough power to make turns on the road. 

There are a variety of differential systems that indicate rotational power and speed. An open differential is the most common differential and is present in most vehicles. Meanwhile, locked differential systems are used for off-road vehicles that may require a faster axle shaft for rougher terrain. 

The more often the wheels are used—which is every time you drive—the more weary the gears start to grind. Differential oil ensures everything runs smoothly enough. There’s also a slight cooling effect that manages the heat-filled transfer of power and moving parts. The fluid depletes throughout use, so you need to get replacements occasionally.

Differential Oil Types

There are two main differential oil types. The first is mineral oil, a liquid derivative of distilled petroleum from crude oil. Some manufacturers utilize this to produce gasoline, cosmetics, and other products. However, automotive fluids such as differential liquids are typically unrefined or mildly treated to maintain viscosity. 

While mineral oils’ effectiveness continues, keep in mind that their chemical properties are still dangerous, and exposure to them is associated with skin cancer. If you’re using these varieties, be careful when handling your differential fluid changes in the future.

The second differential oil type is synthetic differential fluid. It’s created in a lab with other chemicals to mimic mineral oil’s lubrication. With advances in science, some auto enthusiasts believe these liquids offer a better performance to a certain degree.

One common question people ask when figuring out how to change differential oil is whether the replacements are different for the front and rear differentials. Most drivers will use the same variant, like synthetic oil, for both systems. However, fluids with a thicker consistency may be more suitable for the rear differential, too. 

How to Check Differential Oil

Differential oil will need to be replaced to keep the gears moving without damage. A newer vehicle can be driven up to 10,000 miles before needing an oil change, but it’s still a case-by-case basis.

Changing differential oil too early can waste your product, energy, and time. Changing it too late will likely damage the differential system since it’s operated without lubrication for so long. Drivers need to learn to monitor and check the differential oil levels. 

Here are several instances to look out for. 

Low Differential Oil

Low differential oil means the gears are about to grind against one another. It damages the metal components and generate plenty of heat that can cause engine failure. It’s imperative to replace it as soon as you spot it running out. 

Various sounds, such as whirring gears, hissing, and howling, are symptoms of low differential oil. Some drivers may also feel sudden vibrations due to the lack of lubrication. You can also check the oil light on your dashboard to indicate if you need oil. 

Differential Oil Leak

Like most liquids, differential oil can spill and move around. A proper change should avoid leakage, but you should still be vigilant. If liquids enter the airflow sensor or travel through other parts of a vehicle, it would interfere with operations and render it unusable.

If the levels get unusually low after a fresh refill, you can usually pinpoint a differential oil leak. There could also be a puddle directly underneath the diff system and traces of the liquid on the underside. Repair the source of the oil spot and add fresh liquids. 

Contaminated Differential Oil

Differential oil is subject to contamination in various ways. For example, metal components like the timing chain can leave tiny metal particles in the oil around them. The diff system’s gears also create metal shavings, which makes the liquid grainy. 

Another case of contaminated differential oil is when it simply gets dirty or oxidized. Regular lubricants should be a golden yellow, but it will typically turn into a darker green or brown color when placed in a dirty diff system. 

Differential oil is also capable of contaminating other car parts like the serpentine belt. These liquids destroys the rubber faster when spilled onto it. You need to keep these fluids in the right spot. 

How Much Does a Differential Oil Change Cost?

A differential oil change costs around $80 or more depending on who you get it from. Some services may charge separate fees for the products and labor. You can typically conduct the replacement on your own if you feel more comfortable enough to tinker with the car. 

A differential fluid replacement varies from other oil changes like a transfer case fluid change, as the latter is focused on the vehicle’s gearbox rather than the diff system. If you’re getting a professional to conduct the differential fluid replacement, make sure they understand what they are doing and that they use the correct products. 

Steps to Change Your Differential Oil

Changing your differential oil yourself starts with having the correct set of tools. First, you’ll need the right differential oil type for your vehicle. Synthetic fluid is generally much safer to handle, and it also works well for the systems. You can also get a jack, drain oil pan and fluid pump to help transfer liquids.

Here’s how to change your front and rear differential oil.

1. Start by moving the car to a flat and open surface. Differential car fluid, even when synthetic, has a strong chemical smell. It’s ideal to do this in an open yard space. If you must work in the garage, open as many windows as possible and turn on a fan to help with the ventilation. 
2. Set the parking brake and use the jack to elevate the vehicle for the oil change. You can set the rear on jack stands as you chock the front wheels to lift the vehicle and reveal the differential system underneath. Ensure the car is at an even level to ensure a smooth transition, as angles may cause improper oil flow.
3. When you change the differential oil, there will likely be some remaining fluids from the last batch. Remove the fill bolt on the differential housing and allow it to drain slightly. Place the drain oil pan to catch the liquids from this initial opening.
4. Remove the differential fill plug on top. If the housing doesn’t seem to budge, you may have to screw and loosen the bolts. You can use a pry bar to remove the cover afterward. The drain oil pan is repositioned to catch the rest of the differential oil flow as it drains.
5. Once the drip ends, clean the differential housing to minimize contamination. Spray brake cleaner is easy and hassle-free for both the outside and inside of the diff system. You should also scrape off any dirt and debris lingering. Make sure to look for metal shavings from the gears and remove them. 
6. Start adding the recommended fluid to the filling port using your fluid pump. Refer to the instruction manual of this tool to effectively get every drop in there. Keep the pump secure to prevent spillage on other car parts. 
7. You can torque back the bolts and change the plug to secure the differential system. Make sure everything is tightened before lowering the vehicle from your lifts. Take it for a test drive and jack up the car again to see if everything remains intact.

Maintenance of Differential Oil Levels

Most drivers will forget about their differential oil change as soon as the test drive is over. However, it’s important to run regular inspections for leaks and oil quality, especially the first few weeks after your differential oil change. You can check for oil spots underneath the differential system. Be attuned to the vehicle’s performance and sounds so that it’s working properly. 

It’s also important to take note of your most recent differential oil change and keep it in mind for future swaps. As mentioned, the exact moment you should change the fluids is on a case-to-case basis. However, just because you had it three months ago doesn’t mean you will likely wait three months to change again.

If you used the vehicle more frequently than in the previous period, you would likely have to replace it sooner than before. You can track your miles with a third-party phone app and gauge it by then. However, you can also coordinate with other auto enthusiasts. 

Are There Alternatives to Differential Oil?

No, there are no alternatives to differential oil. The global automotive lubricants market was approximately $72.05 billion in 2022, made up primarily of engine oil, brake fluids, coolants and more. While they may seem to have similar properties, these all serve a different purpose that you cannot use for the differential oil system. 

A differential oil shortage is less likely, but it’s not completely unheard of. Many cars and components aren’t as readily available, which can compromise your vehicle’s performance. There was a short period during the pandemic when there was less road traffic, which resulted in less demand for automotive fluids. 

Luckily, the rise of e-commerce makes it easier to get the differential fluids delivered right to your doorstep. Just remember to purchase from a reputable distributor as you buy these items to ensure authentic goods. After all, you wouldn’t want to damage your car. 

Common Mistakes to Avoid

It’s valid to feel a little nervous about replacing your differential oil when you’re doing it wrong, as many things could go wrong. Here are a few common mistakes to avoid:

• Overfilling or underfilling: While you may have a bottle of differential fluid ready to go, there may be a chance that you will need less than you thought. However, you still want to put enough to grease up the gears. Pay attention to the oil levels while the fluid pump is going and manually stop it. 

• Using the wrong type of oil: There are no alternatives to differential fluid, so make sure you use the right type. Also, you should use the same differential oil type as you did before. If your differential system operates on synthetic oil, it’s better to stick with that variant to minimize complications. 

• Not waiting for the drain: It’s easy to want to go ahead and put the fluid pump into the diff system as soon as possible. However, you should ensure you let out old and contaminated fluids first. Otherwise, your batch of clean oil will only get tainted as well, which will simply repeat past problems. 

Tips to Change Differential Oil

Figuring out how to change differential oil is challenging, especially for first-timers. Here are a few tips you can use throughout the process:

• Consult your manual: Wondering what specific type of lubricant goes well with your personal vehicle? Worried about how much differential oil to measure and add? The vehicle manufacturer’s manual is your best resource for all this information. You can also consult the official site’s forum. 

• Go on a drive first: Differential fluid is already thick enough to lubricate the gears. However, when trying to do a differential oil change in winter or after a long period of not driving, it tends to get even more viscous. This texture makes the draining process so much longer. You can warm up the fluid by taking the car around for a spin. 

• Take your time: Everyone wants to get differential oil changes and other car maintenance done as soon as possible. However, being hasty can lead to mishaps and leaks that will only take longer. Take your time as you work on your car. You should also learn to enjoy it to conduct it more frequently. 

Improve Your Differential System 

It can be daunting to get into your vehicle’s liquids, but it’s a necessary step for maintenance. Learning how to change your car’s differential oil is key to keeping the gears and tires moving at all times. Put this information into practice regularly to keep the differential system optimal.