Signs Of Low Differential Fluid – Explained

Differential fluid, also called gear oil, is a lubricating oil that is thicker than engine oil. As a lubricant, differential fluids protect metallic diff components from premature wear and increase their lifespan. It offers a seamless driving experience when making corners on several road pavements.

The diff fluid functions under high pressure to keep the bearings, clutch packs, and gears well-lubricated at all times. It also ensures the entire differential works smoothly and safely.

If water enters the differential fluid, if gets contaminated, or low, it’ll cause catastrophic damages to the differential. It can also lead to a permanent breakdown. Before damaging the entire differential, it’ll project some symptoms to notify the driver of an imminent problem in the system.

Therefore, this article will focus on the signs of low differential fluid and how to check differential fluids. Take a seat and have a 5-minute read.

Signs Of Low Differential Fluid

Whether you have rear-wheel drive, front-wheel drive, all-wheel drive, or four-wheel drive, you need to ensure that it maintains optimal operation. One of the ways to ensure this is to have adequate fluid in the differential at all times.

Here are the differential low fluid symptoms you should watch out for.

symptoms of bad differential fluid

Strange noise

A common symptom of differential low on a fluid is a weird humming, howling, whining, and whining noise from either front or rear differential. You’ll notice a gradual change in these noises when accelerating, decelerating, and when taking corners.

A grinding or humming noise from underneath a vehicle is usually caused by low fluid or worn-out bearing in the differential or axle.

Overheating differential

Several factors can cause a differential to overheat. These factors include using the wrong fluid type, low diff oil, backlash between ring and pinion, overloading equipment, excessive bearing preload, and worn bearings.

Regardless of the other factors that can result in diff overheating, it is also a symptom of bad differential fluid.

Burnt oil smell

If you perceive a burnt oil smell emitting from the transmission or diff area, it could be a sign of bad or low differential or tranny oil. The fluid is apparently low; hence, not properly lubricating every nook and cranny part of the components.

The smell also signifies that the tranny or diff is overheating because of improper lubrication. The fluid could be a wrong oil type, expired, or too old to lubricate the components properly. Therefore, it’ll cause a metal-to-metal rubbing, leading to excessive friction and metal shavings in the transmission.

The moment you notice a low level or a bad differential fluid, do not hesitate to drain and replace it with new oil.


Vibrations from the front wheels when cruising on a sunny afternoon or during that early morning drive are a symptom of bad differential fluid. It could mean the differential itself is wearing out.

Please; let’s get this straight. Several other faulty components can cause this vibration. So it is best to contact a certified automotive mechanic to track and fix the culprit.

how far can you drive without differential fluid


Q: What does low differential fluid sound like?

Low differential fluids or worn gears will sound like humming or grinding noise emitting from the diff. These noises will also have gradual changes when taking corners, decelerating, and accelerating. Any strange noise should be checked by a certified mechanic and fixed as soon as possible before it escalates to a major repair job.

Q: Can I drive with no differential fluid?

First, let’s look at what the differential fluid does to find out if one can drive without it.

The diff oil lubricates the gears, bearings, clutch packs. It also oils the ring and pinion gears and the entire differential. Lastly, it cools the diff and prevents it from overheating.

Therefore, if you’re asking, how far can you drive without differential fluid? Don’t even think of it. driving without differential fluid will cause metal-to-metal rubbing, which will lead to excessive friction. This means the fluid will overheat, burn itself, and pose safety issues. To say but a few, it’ll cause catastrophic damages to the differential.

Q: How long can you go without changing the differential fluid?

The differential is an important component in cars. It compensates for the difference in inner and outer wheels when taking corners. However, it doesn’t require early oil change like the engine oil.

But if the diff receives improper lubrication, you won’t travel far for a long time. Fortunately, a vehicle can run as long as 30,000 to 50,000 miles before requiring a differential fluid change.

Q: What does diff fluid smell like?

A differential fluid smells like transmission oil or like a mechanic’s garage. The diff oil is thick, dark yellow to black, and smells like. a tranny fluid.

If the differential overheats and eventually burns the fluid, it’ll emit a burning smell like burning rubber. Whenever you perceive a burning smell from the diff, have it checked as soon as possible.

Q: What does differential whine sound like?

A differential whining noise when decelerating means there’s a worn-out or loose pinion gear or bearings in the diff. This may sound like a regular or loud whining noise from underneath the vehicle.

Always diagnose your vehicle whenever it starts giving strange noise. If ignored for an extended period, it’ll escalate and drop expensive repair bills on the table.

Q: What happens when you run out of differential fluid?

Driving without diff oil is never advisable considering the major functions of differential fluid – to lubricate and cool the internal components. When you run out of differential oil, the pinion gears, side gears, spider gears, crown wheels, and other inner components will rub against each other. Consider checking out the symptoms of bad pinion bearings.

At first, the diff will give a howling, whining, and grinding noise. If you continue driving with it, it will cause catastrophic damages to the differential unit.

Q: Is differential oil the same as transmission fluid?

Most motorists use the terms ‘transmission fluid and differential oil’ interchangeably. Is there any difference between them? There are several differences between them, starting from viscosity ratings, heat resistance, and the ability to handle pressure.

However, the fundamental difference between the differential oil and transmission fluids lies in the purpose they are used for. Differential oils are engineered to work in manual gears. In contrast, transmission fluids are manufactured to work in automatic transmissions.

Q: How much does it cost to change the differential fluid?

Differential fluid change is an easy maintenance job. It involves removing the diff cover to drain the oil, reinstalling the cover, and last, refilling the fluid. You can also call this service ‘transaxle drain and refill.’

Because of its simplicity, it doesn’t cost much to change. The cost to change diff fluid is $80 to $90 on average. When replacing the fluid, the mechanic may suggest other system maintenance.

Final words

Now that we’ve seen the signs of the low differential fluid, what happens if you use the wrong differential fluid? Using the wrong diff fluid will cause poor lubrication, system overheating, and possibly, differential failure.

Even a master mechanic may not reverse the damages by flushing the fluid. It’ll require replacing the damaged components and refilling the diff with the recommended fluid.

Therefore, always watch out for the symptoms of a low differential fluid and resolve it as soon as possible. Check this extensive article on the signs of a failed differential, causes, and fixes.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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