Things To Know About Transfer Case Fluids, Oils, and Lubricants

What is a Transfer Case and Why Is Transfer Case Fluid Important?

The transfer case is all about a gearbox which is special and normally found in all-wheel drive and four-wheel vehicles. It is the one which transfers drive power from the engine to the rear and front axles.

In vehicles which are all-wheel drive, the transfer case is the one which helps to shift the power from one axle to the next depending on the condition of the traction. In the transfer case, lubricant fluid helps to be able to keep its gear cool and turning smoothly. To replace this fluid, at intervals which are appropriate, will be able to help in preventing wear which is premature and damage which is normally caused by broken down or contaminated lubricant.

You will need to remember that, when the transfer case fluid is low, the entire transfer case will need to be inspected to check out for leaks.  This can be done through:

  • Checking the fluid condition
  • Draining the fluid if it brown in color or dirty
  • Fill the new fluid
  • Test drive the vehicle and check for leaks

Recommendation

Transfer case fluid needs to be replaced at least after every 30,000 miles. You will need to schedule your vehicle maintenance and any time the transfer case is inspected, you will have to check the transfer case fluid.

Common symptoms that you need to replace the transfer case fluid

  • Car unable to change gears
  • Dirty transfer case fluid

How Important Is The Transfer Case Fluid Service?

The transfer case is a gearbox which is unique to all drive and four-wheel vehicles. It is responsible for sending power from the engine to both the rear and the front axles and shifting power from one to the other depending on the road condition. It is the transfer case fluid which is responsible for ensuring that the components of the transfer case are lubricated well. Whenever the fluid leaks or is contaminated, it is no longer in a position to act as a lubricant and the transfer case can end up having severe damage.

The transfer case is a smaller part of the drivetrain system with its primary function is to engage the multi-axle of the vehicle’s axles. It is normally placed underneath the vehicle and constructed from steel or aluminum housing and consists of a system which is complex containing belts, chains, or gears.

The transfer case normally works by being able to split the engine torque from the transmission, taking it to shafts of output that connects to drive shafts lead to the rear and front axles. Most of the transfer cases in use today can be able to mechanically lock the rear and front shafts, together to ensure that each axle gets an equal amount of the engine torque.

How Often Does My Car Need New Transfer Case Fluid?

With the transfer case fluid being very important along the drive train on four-wheel and all-wheel, it is important to know how often your car will be able to need it. It all depends on various factors with the main one being the manufacturer and type of vehicle which you drive. 

It is recommended that you take a look through the operator manual of your vehicle or whatever paperwork that you have which came with your vehicle to find out the recommended mileage for the change of fluid in the transfer fluid.

An example is a Toyota RAV4 where the Toyota manufacturer recommends replacing after checking the fluid for every 15000 miles. If your vehicle is a Ford F150, the Ford manufacturer recommends replacing the transfer case fluid after 60,000 miles.

The difference is due to the fact of the way the transfer case is mounted on the two-vehicle types. The way the one for Ford is mounted is in a more efficient position, and thus less wear and tear is placed on the fluid. Whichever the case, it is something which highlights the fact that you will need to find out your vehicle’s typical mileage range.

In addition to the mileage, there are other factors which affect how often you will need to change the fluid. This factors might affect the transfer case fluid, making there to be a need for you to make frequent changes. They are offroading and towing.

Offroading: When you are doing offroad driving, it can result in doing the regular change of the transfer case fluid. This could be due to the fact that the mounting of the transfer case is beneath the vehicle without any protection.

When doing offroading, it is normally exposed to all types of contamination such as mud and dust on the surface of the road to submersion as the vehicle passes through water pools and streams. Some of these contaminants will be able to work either way into the transfer case with time, diluting the fluid and a need for replacement.

Towing: This will place a lot of strain on the transfer case mechanism due to the fact that the vehicle is work very hard to pull an extra load. If you use your SUV or truck to tow a hitched load regularly, then you will need to keep on checking on  the fluid of the transfer case and be prepared for a regular change.

How to Replace Transfer Case Fluid – Step by Step

Materials Required

  • Sockets/ratchet
  • Drain pan
  • Wheel blocks/chocks
  • Extraction/filter syringe
  • Wrenches – open/box end
  • Transfer case fluid – you will need to consult your owner’s manual to get the right fluid for your vehicle and the amount to use.

Due to the fact that most SUVs and trucks have enough ground clearance, you won’t require to lift the vehicle up. But in case your vehicle doesn't have enough clearance for you to lay underneath, then you will need to follow the proper instruction for jacking for your vehicle. Even if it is a must that you will have to lift your vehicle, it must be level when you are refilling the fluid.

Draining The Transfer

Step 1: Preparing Your Vehicle

Ensure that the vehicle is cooled for at least 2 hours to avoid handling fluids which are hot. The parking brakes should be set and the block/chock at least one wheel back and front.

Step 2: Draining The Fluid

The fill and drain plugs are normally located facing the rear of the vehicle and transfer case. You will find the plug  for the fill located higher up while the one at the lower end is the drain. Remove the fill plug and then proceed to bring out the plug for the drain. Let the fluid to be able to drain as long as you can so as to be able to extract the maximum amount.

Refilling The Transfer Case

Step 1: Reinstalling The dDain Plug

Once you have drained the fluid completely, you will need to reinstall the drain plug while leaving the refill plug out.  There are some fluid bottles which have a spout top to enable you to squeeze the fluid out. If there is no ample room which is under your vehicle to be able to get into the fill plug, the extraction/filler syringe which is in the required materials list will do the job.

Step 2:Refilling The Transfer Case

There is no dipstick in the transfer case to enable you to check the level of the fluid. The rule is all about refilling it until it is able to spill. But using the syringe or the fluid bottle, you can be able to fill the liquid into the filler plug until you see the fluid running out of it.

Step 3: Cleaning Up

It is time to reinstall the fluid fill plug. You will have to wipe the excess fluid from the transfer case. The used fluid should be disposed of properly. In most instances, your local auto parts store can willingly take in the used fluids/oils and recycle them for you, free of charge.   

FAQs

1. Is Transfer Case Fluid The Same As Differential Fluid?

No. The transfer case normally acts as a differential but it does channel its power to two differentials which are located on two different axles instead of to two wheels on the same axle as it is the case with the differential fluid. Both transfer case and differential require fluid to be able to lubricate the shafts, the gears, and the bearing where the metals slide over other metals.

2. What Are The Symptoms Of A Bad Transfer Case?

Symptoms include:

Difficulty in shifting gears: The seal which keeps the fluid inside the transfer case is very important for an operation which is smooth of the transmission of the vehicle.  When there is a leak in the fluid due to a broken seal, it ends up reducing the fluid volume which is working in the transmission currently.

There is also an occurrence of loss in pressure of the fluid which then causes the shifting gears to be very hard for manual or automatic shift transmission. If you notice that you are having difficulty in shifting to lower or higher gears, you will need to conduct a professional mechanic who will inspect what the problem could be and get a solution for it.

Grinding noises which comes from underneath the vehicle: When there is a breakage of or wear of the output shaft seal, it can cause noises to appear from under the vehicle. In many cases, these noises are normally caused by a reduction in the lubricants which are inside the transfer case or it might be a case of metal to metal grinding. When there is metal to metal grinding, that is not a good thing and thus, any time you hear grinding noises coming from your transmission location, you need to check it out or contact a mechanic.

Vehicle jumps in and out of the four-wheel-drive: With loss of fluid, there is a possibility of vehicle jumping in and out of the four-wheel-drive instead of staying in operation. This is normally due to broken parts which are inside the transfer case which controls the operation. The part is prematurely worn out due to fluid leakage which mostly is caused by the output shaft seal.

Whenever the seal leaks, you will be able to notice a reddish fluid on the ground under your vehicle. This is normally the transmission fluid and a sign that the gasket or seal on your transmission case is broken and you will need to repair it.

3. How Much Does It Cost To Change The Transfer Case Fluid?

Averagely, the cost of transfer case will depend on the model and make of the vehicle you are driving. There is also an additional cost of labor to the price of the unit and it can be between $350  to $850.

4. What Kind Of Transfer Case Fluid Do I Need?

Full-time systems use SAE 10W – 30 or 10W – 40 engine oil while the conventional transfer cases will require SAE 80W-90, or SAE 80W GL-5 gear lubricants. For conventional transfer cases, you will also require DEXRON II fluid for transmission.

Read more: 8 Best 0w-20 Synthetic Oil Reviews

5. What Is The Difference Between A Center Differential and A Transfer Case?

Differentials: Cars have two differentials with one located between the two rear wheels while another one is located between the two front wheels. They are the ones which send the torque from the transmission or driveshaft to the drive wheels. They also allow the right and left wheels to speed at speeds which are different when you are moving around a  turn.

When going around a turn, the outside wheel follows a different path as compared to the inside wheel and The wheels at the rear will be able to follow a differnt pathas compared to the front wheels making the wheels to spin at different speeds. It is the differential which enables the difference in the speed between the rear and front wheels and the inside and outside wheel.

There are various differentials which are used in trucks and cars. The differential types can have a big impact on how well your vehicle will be able to utilize the traction which is available.

When having an all-wheel drive, the speed difference between the rear and front wheels is handled by the transfer case

Transfer case: It is a device which is able to split the power between the rear and front axle on a four-wheel drive.  While the differential is able to handle speed difference between the outside and inside wheels, the transfer case in a vehicle which is all-wheel drive contains a certain device which allows for a difference in speed between the rear and the front wheels.

This could be a center differential, viscous coupling or any other type of gearset. They are the devices which allow the all-wheel-drive system to be able to function properly on whatever surface. Transfer case found on a part-time four-wheel-drive system is able to lock the rear axle driveshaft to the front axle driveshaft and thus, the wheels are forced to spin at the same speed.

The above will need that the tires are able to slip when the car goes around a turn. The systems which are part-time should only be used in the situation of low traction in which it is easier for the tires to be able to slip.

6. What is AWD fluid?

AWD is all-wheel drive. The fluid which is a differential fluid which is able to lubricate all-wheel drive (AWD), front-wheel drive (FWD), and four-wheel drive (4WD)

What causes a transfer case to break?

The transfer case normally completes the activation between neutrals of two-wheel drive,  to low of four-wheel drive, and then to drive four-wheel drive. In case a seal leaks, the fluid will pour down and it will not be in a position to be able to lubricate the interior components properly in the transfer case. This is the process will make the parts inside to wear out, overheat and break.

7. What Is A Full-time Transfer Case?

The transfer case can be referred to as the heart of your four-wheel drive vehicle system. it can be part-time or full time and with some models coming from the factory with passenger or driver side front driveshaft output.

All-wheel drive (AWD) vehicles mostly remain in four-wheel drive all the time. That is what is referred to as full-time four-wheel-drive transfer case which operates very transparent to the driver.  They are designed for better handling in light terrain and bad weather but they are not normally considered for off-roading.

In most instances, the high range of a full-time transfer case is at 1:1 ratio for every turn of the output shaft, there is always one turn at each of the axle shafts.

Source: 

  1. https://auto.howstuffworks.com/car-driving-safety/safety-regulatory-devices/never-changed-oil.htm
  2. https://www.testingautos.com/car_care/how-often-to-change-gear-oil.html

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