Transfer Case Fluid: Why It Matters, When to Change, & How to Do It

We’ve always seen multiple fluids and oils designed for different purposes at automotive shops. But why are these fluids important, and everybody wants to get them? The transfer case produces considerable heat and friction like the engine and transmission. So, to ensure the transfer case functions appropriately, a specialized fluid (lubricant) known as transfer case fluid is a must-have. It prevents excessive wear and damage to the transfer case and should be changed regularly. It cools and greases these parts to prolong their lifespan. Read on to find out more about this fantastic lubricant.

How Does Transfer Case Fluid Work?

Transfer Case Fluid Working

The transfer case is the vehicle component placed on the back of the transmission. It divides power between the front and rear wheels of a 4WD or AWD.

First, transfer case fluid coats the internal layer and provides a protective layer. This protective layer decreases friction produced by movement and physical contact. Eventually, enough lubricating draws heat away from the gears and preserves the life and performance of the car. At the same time, a new batch of lubricant then enters the transfer case. This helps clean the components and prevents any dirt and moisture from reaching them.

How Often Do I Need to Change the Fluid?

While the transfer case fluid is an important element for smooth driving, it is also essential to know how often your car will need it. Transfer case fluid doesn’t last a very long time. It easily gets contaminated by carbon buildup after cooling down and becomes less effective at cooling and greasing the components. Generally, manufacturers recommend different maintenance intervals based on the vehicle type and intended use. Checking it every 20,000 miles (32186.88 km) to 30,000 miles (48280.32 km) is a good approach. Moreover, some cars noticed elongated service life, up to 100,000 miles (160934.4 km), but that’s an exception.

Best Way to Replace the Transmission Fluid

Transmission Fluid Replacement

Many trucks and SUVs already have enough space underneath, so you usually don’t need to lift them. But if there isn’t enough room for you to get underneath, make sure to check your vehicle’s jacking instructions. Here’s the method to change the fluid like an expert.

Step 1: Get Your Car Ready

Wait for your car to cool down for at least 2 hours before dealing with the fluid. Also, make sure to set the parking brakes and place a block behind the wheel. 

Step 2: Fluid Draining

Look for the fill plug to drain the fluid; it’s usually at the back of the vehicle near the transfer case. Take out both the fill and drain plugs, and let the fluid drain out for as long as you can to get the most out.

Step 3: Reinstalling the Drain Plug

Now, put the drain plug back in and leave the refill plug open. If you can’t reach the fill plug, you can use an extraction or filler syringe to get the job done.

Step 4: Refill the Transfer Case

Unfortunately, you can’t check how much fluid is in there. Just fill it up until it starts coming out, using a syringe or the fluid bottle.

Step 5: Cleaning

Now, put back the fluid fill plug. Wipe off any extra fluid from the transfer case and properly get rid of the used fluid. Some auto parts stores will take it from you and recycle it for free.

Step 6: Start the Vehicle

Start the car and allow it to rest for some time. This way, the new fluid will be distributed throughout the transfer case.

Step 7: Check for Any Leaks

After replacing the transfer case fluid, check for any leakage from the drain plug or filter. By chance, if you notice it, simply tighten the plug or change the gasket or filter.

Symptoms of Poor Transfer Case

Signs of Poor Transfer Case 

The transfer case is expected to have a long lifespan, but it doesn’t always turn out that way. Here are some common symptoms of having a poor transfer case.

  • The problem with gear shifting. 
  • Grinding, growling, or humming noises come from underneath the vehicle.
  • Greasy puddle formation directly under the transfer case’s location.
  • The problem is staying in 4WD.
  • 4WD Warning Light Illuminates.

Why is It Important to Service the Transmission Fluid?

The fluid in the transfer case keeps its parts lubricated. But if the fluid gets dirty, it can’t lubricate well and may lead to serious damage. If you hear strange sounds, see leaking fluid, have trouble shifting gears, or notice a burning smell, it’s time to see a mechanic and get the transfer case serviced. Otherwise, the transmission fluid’s ability to absorb heat to regulate temperature will diminish, and transmission will deteriorate.

Transmission fluid service will prevent transmission issues and keep the vehicle working optimally. This process removes old, worn transmission fluid and replaces it with new to maintain your car.

Types of Transfer Case Fluid

Transfer Case Fluid can be conventional or synthetic, depending on how they are made. Conventional fluid is extracted from crude oil refining, while synthetic, as the name suggests, comes from the laboratory. Most transfer cases are packed with an automatic transmission fluid (ATF); the other options can be thick gear oil or specialty lubricants. From these options, the question arises: what’s the best transfer case fluid? Well, engine oil is certainly not the best choice. A specific fluid that increases peak efficiency is recommended for a 4WD system of an off-roading truck.

Differential Fluid vs. Transmission Fluid | Transmission Case Fluid

You must have noticed the similarities between differential fluid, transfer case fluid, and transmission fluid. These act as cooling lubricants for vehicles. However, these lubricants are different. Differential fluid, also known as gear oil, is for vehicles with manual transmission, while transmission fluid works specifically with automatic transmission vehicles.

Transfer case fluid is usually brown, blue, green, or yellow. The differential fluid is blue/green, and the transmission fluid case is often a clear fluid with tones of red. The other difference is their lifespan. Although they require regular replacement, their lifespan differs from each other.

Transfer case fluid and transmission fluid need regular replacement. However, the two lubricants have different lifespans. It’s rare to replace both fluids at the same time.

Check out our comprehensive guide for transmission fluids.

Common Problems and Their Solutions

Common Problems with Transfer Case 

Few problems can arise with transfer cases, and fixing them on time can prevent severe damage – one common problem is leakage. If you notice any fuel leakage from the transmission, determine its source and take it to an auto shop. The other common problem is noise coming from the transmission case. It can be due to worn bearings. If you’re having issues with your transfer case, it’s better to get help from a reliable mechanic instead of trying to fix it yourself. 

How to Pick the Best Fluid for Transfer Case?

The ideal way to pick the best fluid for your transfer case depends on the vehicle manufacturer’s manual. You can get the information for ideal Transfer Case fluid by looking at the appendix. When you notice it is always working properly, there’s no doubt you have used the proper fluid and maintained it.

A Lubricant That Every Vehicle Needs

When it comes to maintaining your car and extending its lifespan, we cannot neglect the fruitful outcome of selecting the right type of transfer case oil and changing it occasionally. Don’t damage your transfer case by not getting its fluid change. Whether you DIY it or take it to an expert mechanic shop, getting it changed is a part of the healthy maintenance routine. You can consult the owner’s manual or a qualified mechanic’s opinion on the type and frequency of transfer case oil changes to keep everything in order.

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