Several vehicle system components use fluids to cool and lubricate their internal parts. The fluids or oil keeps these components running optimally until the end of their shelf life. Some of these fluids or oil need replacement after every few thousand miles, while the diff travels over 30,000 to 50,000 miles before needing replacement.
For example, the engine oil should be changed every 5,000 to 7,500 miles, while the differential fluids take 30,000 miles before needing replacement.. Though it takes longer to change the differential oil, most folks still forget to change the diff oil. If you never change differential fluid and have driven past the recommended interval, you are attracting some dead ends to the differential.
In this article, I’ll outline the consequences of not changing the diff fluid, the benefits of changing it, and how many years the diff fluid lasts. You’ll also learn what a differential fluid change is. But first, what is a differential fluid?
Differential fluid Explained
The differential allows each wheel to spin at its unique pace. It distributes the engine power to the wheels and allows them to act according to the driver’s demand.
The differential incorporates several internal components like ring gears, pinion gears, side gears, axle shaft side gears, axle shaft, pinion shafts, bearings, and other components. These components constantly engage with each other as you drive.
These metal parts constantly in touch with one another need a lubricant to cool and lubricate them to prevent accelerated wear and overheating. The lubricant poured into the differential unit is called the differential fluid or oil.
In simple terms, differential fluid is the fluid that lubricates and cools the internal differential parts to reduce friction and wears, and maximize the differential shelf life.
The diff fluid comes in different viscosities. And since auto manufacturers use different technologies in designing their cars, they recommend different oil viscosity. In other words, while other diff fluids do the same work, stick with only the manufacturer-recommended fluid.
What is differential fluid change?
Like every other fluid change in a vehicle, differential fluid change is the act of replacing the differential fluid with a new one. During the replacement, a service technician will drain the old or contaminant diff fluid and pour in fresh fluid. By changing the fluid as recommended, the differential unit will function at its peak performance and reach its life span.
What Happens if you never change the Differential Fluid?
I have this concern in my head; why is it that you have never changed differential fluid on your truck or SUV? Oh! Come on, man, differential fluid change only takes place after covering 30,000 to 50,000 miles and doesn’t cost much.
If you have never changed your differential fluid, the internal diff components will suffer accelerated wear and tear and extreme overheating. Other issues include irritating noise when driving, differential failure, and reduced vehicle efficiency.
Increased wear and tear
Every car manufacturer recommends a differential fluid with a certain viscosity rating. Plus, the diff fluid should be in the right conditions. Over a long period, the fluid will be contaminated and filled with metal shavings. If the diff fluid is not changed when necessary, it’ll cause increased wear and tear in the unit.
When there’s increased wear and tear, the internal components like different gears, pinions, and bearings will not function as they should. When this happens, the differential will struggle to transfer power between the wheels.
Usually, accelerated friction will cause too much heat in the unit. And if this continues for long, the internal diff components will suffer extreme overheating.
Under normal conditions, the gears, bearings, pinions, and other system components make contact as they reciprocate. As you know, this is normal. But if the fluid becomes contaminated, the metal-to-metal contacts between these internal parts and the contaminants in the oil will cause the diff unit to overheat.
The thing is, overheating differential does not only strain the entire diff unit, but it also affects the vehicle’s performance.
Irritating noise underneath the vehicle
There’s nothing more frustrating and embarrassing to me than hearing irritating noise when driving with a friend or a colleague. But this is it; if you have never changed rear differential fluid, be ready to get embarrassed someday. A contaminated diff fluid will cause irritating noise that sounds like a bad wheel bearing or a lousy universal joint.
But if you change the fluid as your car manufacturer recommends, you’ll enjoy the diff assembly. This component lasts the lifespan of the vehicle or, at least, fails after covering 150,000 to 200,000 miles.
Also, irritating noise from the diff unit is one of the signs of low differential fluid. So, check the fluid level if the diff is making noise earlier than it should. It could be there’s a leak somewhere in the system.
If you have driven your vehicle past 100k miles without changing the fluid for once, there could have been accelerated friction, wear and tear, and extreme overheating in the system. All this, put together, can cause the diff to fail.
Maintaining a differential is easier and simpler than replacing a damaged one. A lousy differential repair will cost from $500 to $1,000, but changing the fluid won’t cost you more than $100.
Hurts vehicle efficiency
The primary function of the differential is to distribute engine power to the individual wheels so they can operate at their unique pace. If you have never done front and rear differential fluid changes, it’ll affect the vehicle efficiency because the engine power is not effectively distributed to the individual wheels.
In some extreme cases, you will experience a slight increase in your gas consumption and a decrease in throttle response. All you need to fix these problems is to replace the fluid.
How many years does differential fluid last?
Differential fluid stays longer than most other fluid in a vehicle before needing replacement. The major difference between the diff fluid, transmission fluid, and engine oil is that the diff fluid doesn’t need to be filtered.
Based on car manufacturers’ recommendations, differential fluid lasts 3 to 5 years or 30,000 to 50,000 miles. This is an easy-to-do job. Any DIYer with the right guide can change the diff fluid.
You have seen what will happen if you fail to charge your differential fluid. Now, let’s look at the benefits of changing rear differential fluid.
What are the Benefits of changing rear differential fluid?
As I always say, the owner’s manual is the manufacturer in print. It is like the manufacturer telling you what to do every time.
Changing the differential fluid as recommended by your specific owner’s manual offers the following benefits:
- Better road grip
- The differential will be cleaned of the contaminants that could cause internal damage.
- Your car will become more responsive as you hurdle down the road
- Vehicle handling, cornering, and wheel rotations become smoother.
At this point, you have learned what could happen if you never change differential fluid on your truck or SUV. So, if you haven’t changed your rear and front diff fluid, now’s the right time to do it. Drive into your trusted mechanic’s garage and have them change the fluid.
Remember, don’t forget to stick to the manufacturer’s recommendations. It pays more to prevent issues than to fix them.