What are the effects of not changing differential oil?
3 Answers
If the differential oil is not replaced, as its performance deteriorates, the friction between the gears in the differential structure will increase, leading to higher vehicle fuel consumption. Over time, this can damage components such as the differential and differential lock, and negatively impact driving quality. Here is some relevant information about differential oil: 1. Differential oil is used to lubricate the rear axle gear transmission mechanism, also known as final drive oil or gear oil. Its primary functions are lubrication and cooling. Due to differences in the axial positions and tooth profiles of gears, the contact stress and relative sliding speed at the gear meshing surfaces vary significantly. Therefore, different types and grades of gear oil are required. 2. During hot summer months, continuous high-load driving can cause the temperature of transmission and differential gear oil to exceed 120°C, leading to oil degradation. Additionally, automotive lubricants are prone to loss under high temperatures, reducing their lubrication effectiveness. In severe cases, this can result in gear and bearing failure. 3. The composition of differential oil is somewhat similar to engine oil. Compared to engine oil, differential oil not only provides lubrication, anti-wear, and cooling functions but also offers better thermal stability. During high-speed driving, the temperature of the lubricating oil in the differential can become extremely high, far exceeding that of the engine oil. At this point, the high-temperature viscosity characteristics of differential oil become particularly important. As a lubricant, differential oil also has corresponding viscosity grades. The selection of differential oil depends on factors such as latitude (north or south) and the vehicle's maximum load capacity.
As an average car owner, I remember once forgetting to change the differential oil, and then I kept hearing clicking noises while driving, which was quite annoying. Later, I looked it up and found that differential oil, like engine oil, can degrade and deteriorate over time if not changed, losing its lubricating effect. Increased friction between gears accelerates wear, and the noise will definitely get louder. In severe cases, bearings or gears inside the differential may get damaged, causing the drive wheels to slip or stop turning, especially during high-speed driving or turns, leading to poorer handling. The repair costs aren’t cheap—at least a few thousand yuan. The differential is a key component responsible for balancing wheel speeds, and if it fails, it could affect other parts of the drivetrain. I recommend changing the oil every 30,000–50,000 kilometers as specified in the owner’s manual, preferably using the manufacturer-recommended type, and avoiding adding water or contaminants.
As a family driver, I always worry about car safety. Not changing differential oil poses high risks on slippery roads: degraded oil causes gear jamming, uneven wheel speeds, and easy skidding, especially in rain or snow. Increased noise also distracts driving. If the differential fails, locked wheels could lead to serious accidents. I personally experienced sudden loud noises at low speeds, requiring prompt repairs. Recommended to change oil every 40,000 km to ensure smooth and safe driving.
