Will Thicker Oil Quiet a Rear Differential?

Many people want to quiet a rear differential, but do they really need to change their fluid? You may think that the thicker the oil, the less noise it will make, but this can actually cause more problems. Thick fluid isn’t as good as thin, and can lead to issues with gear tolerances. Thicker fluid will not allow heat to transfer properly to the gears and will not keep the differential quiet.

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If you’re wondering what your car needs when it comes to rear differential oil, you’ve come to the right place. There are two main types of oil: synthetic and mineral-based. Each type has their own benefits and drawbacks. Synthetic oil is better for high temperatures because it resists oxidation. Both types are highly recommended, but there are some key differences to remember before purchasing a new one.

Rear differential oil has a high viscosity, and the thinner it is, the less protection it will offer. Generally, rear differential oils have a viscosity of 75W-90. For 8.6-inch differentials, the oil contains 4.2 pints of gear oil, while a 9.5-inch rear differential uses 5.5 pints. The rear differential casing is located underneath the vehicle and is locked in with 12 10mm bolts. If you need to check the oil level, open the casing with a 3/8″ drive and remove the differential plug. A clean plug will indicate that the gears are not worn down.

The rear differential oil should be replaced when it loses its viscosity. It is best to take your vehicle to a workshop to have it serviced, but if you are unable to do it yourself, there are several steps you can follow. Remove the fill plug first, then loosen the bolts. Leave a few inches of slack, as this may cause your differential to drain. If it sticks to the bolts, try prying the differential open with a flat screwdriver.

The proper weight of the gears is another important factor. The correct GL rating and viscosity are important when choosing the right rear differential oil. Otherwise, you could end up guessing, which gear oil is best. So, what’s the proper viscosity? And what’s the best way to tell? There’s a lot of research out there and you won’t be disappointed.

Gear oil viscosity

A high-quality gear oil is critical to the smooth operation of a geared system. It must lubricate gears, cool them, and carry damaging wear debris away from the gear contact zones, while quieting the sound of gear operation. The gear oil used in manual transmissions, differentials, and industrial machinery gears should be designed for the utmost protection under extreme conditions. While gear oil differs from engine oil, it has the same viscosity and is usually of the SAE 90 variety.

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If the noise is accompanied by a grinding noise or a squeaking sensation, the issue is likely the result of excessive gear movement inside the differential. It’s also possible that the contact pattern between the gears is not properly adjusted. Worn gear contacts will keep on creating a contact pattern, which is noisy and leads to failure. In severe cases, the noise can lead to a total replacement of the rear differential.

A good gear oil viscosity will reduce friction and noise in the rear differential. Liqui Moly, a leading lubricant company in Europe, provides a special viscosity control gear oil that is ideal for extreme loads. However, limited-slip differentials require a different oil. While a higher viscosity is essential for quieting a rear differential, it should be considered only for extreme loads.

The lubricant level is crucial to the proper operation of a rear differential. It’s best to make sure it’s at least 1 percent higher than the recommended level. If it’s not enough, check the viscosity of your gear oil by using the link below. You’ll be surprised to see the difference. It’s easy to make sure that the oil is right for your vehicle, but it’s important to make sure that the viscosity level is the right one.

Lifetime fluid

If you’re looking for a way to quiet a rear differential, one option is to use a synthetic fluid. While synthetic fluids will require replacement at some point, they won’t need to be changed as often. A synthetic fluid will not work as well when water gets into the rear differential, which is the only real concern. If you’re interested in a natural, non-toxic fluid, a solid rear axle is likely the culprit. Most solid rear axles are equipped with a plug to drain the fluid and refill it.

After disassembling the differential, you’ll need to drain the existing oil. Be sure to remove the nut holding the gear oil fill bolt. Then, remove the gear oil fill bolt and wipe away any excess oil. You may want to consider replacing the gear oil if the seal is damaged. This repair should take three to five hours, depending on the amount of oil in the differential. You may want to consult with a mechanic if you’re not confident with DIY repairs.

If you notice a whining sound coming from the rear differential, it’s likely the rear differential. The differential is located where the driveshaft meets the axle, inside the bulge. A whining rear differential can be caused by a number of problems, from bad pinion gears to faulty side seals. To determine the cause of the whining, check the differential’s oil and inspect the gasket.

Rear and front differentials both require replacement of fluid every 30,000 to 60,000 miles. The frequency of change depends on the vehicle and driving conditions. If you drive primarily on the highway, it’s likely to be enough. If you haul supplies, though, you may need to change the fluid more often. Check with your dealership or owner’s manual to ensure that the recommended interval is sufficient for your car model.

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Increasing viscosity

Increasing the viscosity of your rear differential oil can make it run more smoothly. You can think of these additives like a slinky. These products will open up as the temperature goes up, but they will still return to a 75-weight viscosity at cooler temperatures. This is especially important when driving in extreme temperatures. If you have a problem with a noisy rear differential, you can increase the viscosity of the oil.

There are many different reasons to increase the viscosity of the oil in your rear differential. A pitted bearing can cause noise, which is usually a “rumbly” sound that can be annoying to drivers. Another cause is the interaction of the ring and pinion. Gear oil additives do not wear down with normal driving, but they do deplete if the oil is contaminated with water or metal.

Higher viscosity oil provides more on/off power steering. The lighter oil increases the on/off power steering and makes it easier to get out of a hole without throttle control. However, if you have a rear differential with less traction, it may be harder to control the front clutch wheel during corners. Heavy oil may also cause the rear end to swing out as it loses traction.

While increasing viscosity will not completely stop a noisy rear differential, it may prevent it from squealing. You can also increase the viscosity of the oil by increasing the amount of oil in the rear differential. While this isn’t guaranteed to solve the issue, it will help the vehicle operate more smoothly and quietly. Just remember to always maintain proper maintenance, and use only oil with the appropriate viscosity.


When buying new oil for your rear differential, make sure to read the manufacturer’s recommendations. Different types of oil have different properties. Mineral-based oils are typically less durable than synthetic oils. Synthetic oils are more resistant to thermal decomposition and oxidation, making them a better choice for high operating temperatures. Follow the recommendations on the package to ensure proper lubrication and long life. If you’re unsure, consult a mechanic or differential oil seller.

A basic type of gear oil is GL-1, and it was developed for certain settings and lighter operating modes. Another important property of differential oils is viscosity, which is listed in the vehicle’s manual. It’s easy to find this information online, at service centers, or at specialized automotive stores. Differential oil viscosities correspond to operating conditions and differential types, so make sure you know your vehicle’s specific needs.