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Differential Fluid Change: Is it Really Necessary?

Differential Fluid Change: Is it Really Necessary?

Owners of vehicles with rear-, front-, or all-wheel drive terrains like cars, trucks, and SUVs might have probably been asked if they want a differential fluid change when they visit service shops. It is something one doesn’t hear quite often. There’s a regular engine oil change which is very important. Then there’s the radiator fluid that you have to check regularly and maintain, too. But what is a differential fluid change? Is it really necessary? What is it for? 

Auto Repairs Are EXPENSIVE

Differential Fluid Change: What is a differential?


To better understand if a differential fluid change is necessary, we have to know what a differential is and what it is for. 


A differential is a part of your vehicle’s rear and front axle assembly that makes up for the difference in distance that the outside wheels and the inside wheels travel when your vehicle turns or drives through corners. It is because when you make a turn, the inside wheels travel less compared to the outside wheels. If all the wheels spin at the same speed while turning, the car will wobble. Your car’s differential prevents this from happening and it makes sure that your wheels move independently every time you drive through corners and turns. It allows your wheels to turn at different speeds. 

Differential Fluid Change: What happens if you don't change differential fluid?


Car owners know that in order to keep their cars healthy, they need to follow their cars’ recommended schedule of maintenance and service. It should be done religiously even if your car doesn’t show any signs or symptoms of a faulty component. 


Among all of the car’s maintenance and services that need to be done, the differential fluid change is often neglected by car owners. 


Just like an engine oil change, a differential fluid change is vital too to keep your car in good working condition. Differentials deal with moving parts that involve metal to metal contact that produces heat from friction. The said contact can also wear down its surfaces and eventually weakens its gears that can lead to failure.


Differentials operating in extremely high temperatures can also lead to thermal breakdown of the differential fluid which could result in deposit formation and loss of lubrication. When this happens, its gear will grind leaving behind metal shavings and other waste. 


To keep the differentials in their optimum operating condition, it needs to have proper lubrication. This can be achieved by following the recommended differential fluid change schedule set by the manufacturers.


Differential Fluid Change: How often does the differential fluid need to be changed?


The differential fluid plays a very important role in making sure that your car drives through turns and corners right. It is a thick, dense liquid, thicker than a motor oil made to keep your differential properly lubricated while it compensates for every turn and cornering made by your vehicle.


When you plan for a differential fluid change and how often it should be performed, the answer will vary depending on a lot of factors. Most car manufacturers recommend that you perform a differential fluid change every 30,000 to 60,000 miles. Like many of the car’s oil, fluid, and parts, the differential fluid also gets contaminated over time and breaks down because of heat. If it is left too long and neglected, the fluid may start to run low. 


Sometimes, a differential fluid change might be needed before you hit the recommended miles if your differential fluid has been contaminated with water or other substances. Vehicles with contaminated or low differential fluid can result in your differential running noisy and can cause it to fail. The gears can seize that locks your wheels which can potentially cause a lot of damage or accident. 


If your vehicle is being used in extreme operations, its differential fluid change should be more frequent. Like when you often use your vehicle to tow at wide-open throttle or when you drive frequently at above 70 degrees Fahrenheit temperatures


When you decide or consider performing a differential fluid change on your vehicle, you need to choose the right differential fluid. You need to consider its proper weight, viscosity, and GL rating. You have to make sure that you are using the right fluid to ensure that you will be provided with the optimum lubrication your vehicle needs. You can always refer to your owner’s manual to know the specifications needed for your differential. 

Differential Fluid Change: What are the signs of a bad differential fluid?


Automotive lubrication fluids play a very important role in the vehicles’ overall performance, condition, and service life. Low or bad fluids can cause problems and damages that can be costly to fix.  One of which is the differential fluid or the gear oil that lubricates the differentials and the manual transmissions. Most of the time, drivers wait for the early signs and symptoms of a bad fluid or oil before they set a schedule to have it changed. 


It is always best practice to not wait for your differential fluid to go bad before you perform a differential fluid change. But for some reason you forgot about it, here are some of the early signs or warnings that let you know that your vehicle is due for a differential fluid change. 

  • Your vehicle exceeds its recommended differential fluid service interval.


If you check your vehicle’s mileage and realize that it exceeds the recommended differential fluid service interval, it is a sign that it is due for a fluid change. That is why it is important that you know the differential fluid’s service interval by checking your owner’s manual. Keep in mind that an old, neglected differential fluid can’t provide the same level of protection as a clean, new oil or fluid does. Keep your differential fluid clean and fresh by following the recommended fluid service interval. 

  • Noisy transmission or differential. 


Another sign that it’s time for a differential fluid change is when you have a noisy transmission or differential. When the differential fluid runs too low or gets contaminated, it could lead your gears to howl or whine whenever your vehicle is turning or cornering. This happens when there is no proper lubrication and the noise may increase when the vehicle speeds up. 


A whining differential or transmission should not be driven. It should be checked and inspected immediately to avoid any serious damage. 


  •  A burning smell from your differential.


If you notice a burning smell coming from your differential or gearbox, it could be an indication that your vehicle needs a differential fluid change. The burning smell can be caused by an overheating gearbox because of poor lubrication. Dirty and contaminated oil can’t properly lubricate the moving metal parts that can result in burning oil from the high temperature. A differential fluid change can help fix this problem.


The burning smell can also come from an old seal that is leaking oil. You can check under your vehicle’s parking spot for any visible reddish stain. If you are certain that there is an oil leak, you may have to replace or seal or gasket to get rid of the problem.   


  • Jerking transmission or gearbox.


A jerking transmission or gearbox can be caused by a lot of factors but a low differential fluid level can cause it too. If the fluid level in your reservoir is too low, it could result in gears grinding and slipping. It’s good to develop a habit of checking the fluid levels of your vehicle including your differential fluid to ensure that your vehicle has the appropriate amount of fluid. 


If you have already topped off your differential fluid but the jerking continues, you need to have your transmission system checked and tested for other possible problems. 


Differential Fluid Change: How do you check differential fluid levels?


Differentials need differential fluid or commonly known as gear oil to lubricate and cool down its internal bearings and gears. Make it a habit to check its level and for any signs of leaks. 


To check your differential fluid, you need to do the following steps.

  • Find the differential fill plug and loosen it.


The differential fill plug is usually located on the differential itself or on the differential front cover. When you find the square or hex shape fill plug, loosen it using an appropriate tool. Make sure that you place an oil drain pan under the differential before you loosen it. 

  • Remove the fill plug.   


You would know if the differential fluid is low if there’s no fluid running out when you remove the differential fill plug. 


If the fluid level is low, you will need to add the appropriate amount of differential fluid. 


Step 1.  Add the right amount of fluid until it starts to leak out. Make sure that you are using the right fluid or gear oil. 


Step 2.  Put the differential fill plug back on and tighten it with the right tool. Make sure that you tighten it until it is snug. 


Differential Fluid Change: How do I change my vehicle’s differential fluid?   


Performing a differential fluid change can be messy and if you are sensitive to its smell – it could smell like a rotten egg – then it is better than the differential fluid change is handled and done by the professionals. 


If you want to do the fluid change yourself, it can be easy. It is messy, but it’s doable. You will have to prepare yourself and wear the right gear. Wear clothes that can be thrown away just so you won’t have to deal with the smell after. 


Step 1. Prepare the area.


A differential fluid change can be messy. Some differentials have drain plugs while others will require you to have the housing covers removed. To minimize the mess, you need to prepare a wide catch pan with a plastic drop cloth. It is said that driving your vehicle for a few minutes, just to warm up the oil can help. 


Step 2. Secure your vehicle by using jack stands.


You need to secure your vehicle using jack stands or ramps to access your differential’s drain and fill plug. Make sure that it’s secure by getting your vehicle on level ground. Keeping it level even when raised up can help ensure that the right amount of fresh fluid makes its way into your differential. 


Step 3. Locate the differential fill plug, loosen it and take it off. 


If your differential has a drain plug, unscrew it. Make sure that the catch basin is already placed under it since all of the fluid will come out. Allow the fluid to completely drain until the last drop.


Step 4.  Replace the drain plug. 


Use a new washer and use the appropriate tool to ensure that you won’t damage the threads, Wipe the case from any excess fluid. 


Step 5. Refill the differential fluid. 


By using a pump, slowly refill your differential fluid. Make sure that you are using the right fluid recommended by the manufacturer. Fill it with the recommended amount of fluid or until it starts to trickle out the fill hole. 


Step 6. Reinstall the fill plug and tighten it. 


Reinstall the fill plug and tighten it securely. Wipe any excess fluid and make sure everything is clean,


For differentials without a drain plug.


Remove the fill plug and unscrew the housing bolts if you don’t have a drain plug. Leave some bolts on top loosely fastened to hold the cover in place. Pry open the cover slowly using a screwdriver. Be careful to not mar the surface of the housing as the differential fluid gushes out. Let it all drain.


Clean the housing, gears, and the wet side of the housing cover. Wipe all the remaining fluid out. Bolt the covers in place and tighten the bolts with a torque wrench. Fill it with a fresh differential fluid up to the brim. Reinstall the fill plug and tighten it. 

Differential Fluid Change: Conclusion


Differential fluid change is necessary. The recommended change intervals might be much longer than the engine oil’s but it doesn’t mean that you can just forget about it or neglect it. You still have to do your part and check it to make sure that it doesn't cause problems for you later on.