When Should the Transfer Case Oil Be Changed?
One of the most important components of a drivetrain on a 4x4 or all-wheel drive (AWD) vehicle is the transfer case. Its function is critical to the vehicle going anywhere and like all parts of the drivetrain it requires fluid to reduce friction and work smoothly.
Let’s start with the basics.
What is a Transfer Case?
If your vehicle is equipped with 4x4 or AWD, then it uses a component called a transfer case to send power via drive shafts to both the front and rear axles. This is the piece of the system that mechanically allows you to switch between 2 wheel drive, 4WD High, and 4Lo. There are a few different kinds of transfer cases that will affect the ability of the vehicle in different ways.
What Kinds of Transfer Cases are There?
A transfer case will generally use either a gear or chain mechanism to transfer the power to the drive shafts. It is a piece of precision machinery. There are a few sizes and housing variations. A ‘married’ housing configuration refers to the transfer case being bolted directly to the transmission, where an ‘independent’ or ‘divorced’ housing is further down the driveshaft.
Using different gear ratios (4:1) provides a mechanical advantage for added power when switched into 4Lo. This is why the speed of the vehicle drops when switched into 4Lo. The drivetrain is spinning 4 times into the transfer case for every single rotation it puts out. The energy is not lost, however, it is gained in the form of power, rather than speed.
This is similar to how a pulley system works, for readers who are familiar with that concept.
The 1:1 ratio allows direct power transfer so the vehicle performs at the same speeds in 4WD as it does when in 2WD.
Aside from these technical variations, the three basic kinds of transfer cases are:
● Part-Time 4WD
The most common type of transfer case. Allows the driver to switch between 2WD, 4Lo, and 4 High - hence part-time.
● Full-TIme 4WDThe simplest design - always sends power to both axles. This will often have a high ratio differential to help minimize drive binding.
● Active 4WDThis design uses computer technology to detect wheel slip and send power where it is needed without driver input.
When Should I Replace The Oil In My Transfer Case?
It’s important to understand that every vehicle is different as such, drivers should always consult their owner’s manual. That’s because different manufacturers use different fluids, which have different lifespans.
As a general rule, however, it’s important to change the oil in the transfer case every 30, 000 miles. Now, if you are a little harder on your drive train - for example, towing a work trailer or off-roading, then it’s best to check it every 15, 000 miles or so, to be safe.
For drivers wanting to do it themselves, there is good news! It’s very easy to change the fluid.
It’s going to be up to the owner to make sure they have the right oil for their vehicle, so consult the owner’s manual, Google, consult with a mechanic - whatever it takes: get the fluid right! Your best bet may be to schedule a transmission checkup at Best Western Transmission in Colorado Springs and let the local experts help you out.
Once the vehicle is safely jacked up and the transfer case is located it’s a matter of draining the case. Place a drain pan underneath, then begin by removing first the upper threaded plug (the fill plug) then the lower threaded plug (drain plug). Once it’s all drained, put the drain plug back in, fill it with fluid, and replace the fill plug.