Aside from the engine oil, changing the differential fluid is probably one of the most neglected parts during maintenance.
Also known as the gear oil, this fluid protects the differentials just like how the engine oil protects the engine.
The front and rear differential oil change cost more than an engine oil change though.
It usually ranges from $30 up to $200 including the oil, parts that may need replacement, and labor.
|Midas||$30 – $175|
|Pep Boys||$50 – $170|
|Sears||$60 – $190|
|Your Mechanic||$75 – $168|
Below are some of the chains that offer gear oil changes with prices subjected to additional taxes and fees. Chains like Goodyear, Firestone, Jiffy Lube, Mr. Tire, and Valvoline also offer this service.
You may contact any of these auto shops and dealers to get your car’s front or rear differential service cost estimation as well as discounts.
The Differential and Differential Fluid
Imagine as you turn in to a corner when driving, what would happen if all of your wheels turn at the same speed at the same time?
Don’t worry, the result will not be catastrophic. It will just put unnecessary strain on different parts of your car, especially the tires and the whole drivetrain. What’s catastrophic is the money that you will spend on future repairs.
That is where the differential comes in. It is part of the front or rear axle assembly. The axle is the shaft in the center. The wheels of the vehicle rotate around it.
The differential transfers and distributes power to the wheels and compensates for the difference in distance whenever a car turns. It basically lets the inner wheels of your car spin faster than the outer wheels when you round a corner.
It is also part of the drivetrain. The whole drivetrain functions together to transfer the rotational power produced from the engine down to your wheels so the car can move smoothly.
What about the differential fluid? Just like the oil to the engine, it lubricates the gears in the car’s differential so that they can shift sleekly and easily. It is usually thicker in consistency than the engine oil so it can withstand the hot temperatures reached in the gearbox.
Gear oils also don’t need changing often since they are set apart from the combustion process. They are sealed in the compartments of drivetrain that protects them from outside dirt and contamination.
When Should You Get Your Differential Fluid Changed?
Most mechanics recommend that the differential oil should be changed every 30,000 to 50,000 miles. Generally, it still depends on your vehicle, driving conditions, habits, and the quality of your differential fluid.
Trucks and cars that often do heavy towing require often differential servicing. It is because the heavy stress makes the components work more; causing a fluctuation in fluid temperatures. This means that the oil would burn faster than when a vehicle runs under normal conditions.
To be sure, you can always check the mileage recommendation in your car’s manual or have a mechanic check the differential oil during regular maintenance services.
You can also check your own gear fluid from time to time if it’s contaminated with metal particles or other substances. The differential is usually located between the drive wheels of your vehicle but take note that some vehicles have a front differential and others have a rear differential.
Types of Wheel Drives and their Differentials
There are different wheel-drives and differentials depending on the type and purpose of the vehicle. It also depends on whether the car is vintage or more of a new generation one. You can learn more about how a vehicle works through its wheel drive system and differentials.
- Front Wheel Drive (FWD): the differential on this wheel drive is often referred to as the transaxle. The car’s transmission and the differential itself share the same housing and gear oil.
The repair cost of the differential on a front wheel drive is usually expensive because the transaxle has to be removed first. Economy and low-cost cars are usually FWD.
- Rear Wheel Drive (RWD): the differential which is located at the back has its own housing and lubrication. The oil of the differential on a rear wheel drive is thick, dark, and usually heavier.
Cars with RWD have better balance and offer better handling. However, traction on slick roads especially in rain and snow might be a challenge. Most police cars, sports cars, and racing cars are RWD.
- Four-Wheel Drive (4WD): four-wheel drive vehicles typically have front and rear differentials that are built in fixed axles. A transfer case rests in between them. 4WD differentials distribute torque evenly on front and rear wheels. One notable quality of four- wheel drives is better traction. Most trucks and SUVs are 4WD.
Types of Differential
- Open: It is the most common and the oldest type of differential. It’s mostly simple and inexpensive but durable. Open differentials split and apply the engine torque into two ways that allow the wheels to spin at varying speeds.
The only disadvantage of open differentials is that when wheels begin to slip, they continue to do so and the power is directed to the wheel with the least grip. This type of differential is usually found in family sedans and economy cars.
- Limited Slip: Ferdinand Porsche developed this variation of differential. It is a combination of open and locking differentials. More commonly known as the “Positraction”, it responds to the traction situation by increasing or decreasing torque whenever the wheels need it. It also locks automatically when slipping happens. Unlike in an open differential, when a wheel slips, it allows more power to be used on the non-slipping wheel. There are three more variations under the Limited Slip Differential: the Viscous LSD which is found in all-wheel-drive vehicles, the Clutch-type LSD, and the Mechanical LSD
- Locking Differential: it locks both axles so the connected wheels always spin in unison at the same speed regardless of traction conditions. It is usually manually activated and then turned off whenever necessary. Locking differentials are ideal for extreme off-road driving that’s why they are usually found in Jeep Wranglers and full-size trucks. However, turning the vehicle with this differential can be very challenging.
- Torque Vectoring: it is the newest and most advanced type of differential. With its sensors, electronic controls, and clutches, it determines which wheel should be getting the most power. It fine tunes the torque delivered to each drive wheel and it can slow down or quicken the car’s turn around a corner. However, it’s heavy, complex, and can be really challenging to maneuver. Torque Vectoring Differentials can be found in the BMW X5 M or the Lexus RC F.
Oil Grades and Specifications
The gear oil’s function is to prevent the contact of metals with each other that causes friction and wears the gears down. A good differential fluid should not only withstand high temperature in the gearbox but should also have the ability to ease heat from around gears as well.
Just like engine oils, gear oils are graded based on their viscosity by the SAE (Society of Automotive Engineers). First, they are divided into two classes: Monograde and Multigrade.
- Monograde: from the word mono, it is designated by a single number. Higher grade number means thicker oil. Some examples of it are the grades used in hotter climate such as SAE 80, 900, and 140.
- Multigrade: it’s the same as the rating on engine oils – multigrades are designated by two numbers separated by a ‘w’ which means winter. The first number denotes its resistance to low temperature while the second number is the resistance to high temperature.
The API (American Petroleum Institute) also rated gear oils by their performance. The GL stands for Gear Lubricant.
|GL-1||Active||For manual transmission under mild conditions. Usually for rust and oxidation protection and without friction-modifying.|
|GL-2||Inactive||For automotive worm-gear axles operating under medium load. It has more additives than GL-1 but also without extra-pressure additives.|
|GL-3||Inactive||For non-hypoid gears under moderate to severe conditions. It has light extra-pressure effect.|
|GL-4||Active||Most used oil. For manual and hypoid gears under moderate to severe conditions. It has moderate extra-pressure effect as well as other additives.|
|GL-5||Active||For hypoid and highly-loaded gears under severe conditions. It has high amounts of extra-pressure as well as other additives.|
|MT-1||Active||For manual transmission. Mostly used in heavy-duty trucks and buses. It provides protection against the combination of thermal degradation, component wear, and oil-seal deterioration.|