The Unsung Heros of Transmissions, Differentials and Transfer Cases

Whether it’s for a manual transmission/transaxle, transfer case or differential, Mopar® has the premium and full synthetic specialty lubricants that are designed specifically for Chrysler, Jeep® and Dodge vehicles.

Forty years ago, selecting gear and axle lubricants was relatively simple. Most of the products available were mono-grade (more on this later). Plus there was just a fraction of the lubricants available in the marketplace in 1968 compared to today.

In the past decade, the use of synthetic lubricants has increased significantly. This has reduced the frequency of drain interval service for many gearboxes and differentials. However, when a vehicle is subjected to extreme conditions, such as trailer towing, a lubricant replacement is often recommended. Let’s take a closer look at these lubricants and when to replace them.

What they do

Gear and axle lubricants in manual transmissions/transaxles, transfer cases and differentials do the following:

• Remove heat and dissipate it into the air
• Lubricate and clean moving parts
• Reduce friction and wear
• Help prevent corrosion

Identification

The American Petroleum Institute (API) has established ratings for gear lubricants. Most automotive gear lubricants are designated by an API service classification “GL,” such as GL-3, GL-4 and GL-5. Some vehicles require special lubricants not classified under the API system.

The Society of Automotive Engineers (SAE) establishes gear lubricant viscosity classifications. Viscosity refers to a lubricants thickness or ability to flow. The more viscous or thicker a lubricant is, the less it tends to flow.

Single vs. Multi-viscosity Grade Lubricants

Many years ago, manufacturers recommended single-grade gear oil. As a result, the lubricant needed to be changed based on changing seasonal temperatures. Today, most auto manufacturers recommend multi-viscosity grade gear lubricants that can provide adequate lubrication to critical parts at both low and high temperatures.

Multi-viscosity lubricants have a dual number, such as SAE 75W-90 which must meet the low-temperature requirements of SAE 75W and the high-temperature requirements of SAE 90. The “W” suffix means that the gear oil has been formulated and tested for low-temperature operation.

Special Lubricants

Some special gear lubricants do not carry a viscosity number, as the viscosity is part of the specification followed in formulating the lubricant. Furthermore some manual transmission/transaxles and transfer cases require automatic transmission fluid, such as Mopar ATF+4.®

Maintenance

Chrysler LLC has a separate maintenance schedule “B” with recommendations for severe service conditions—as outlined in the owner’s manual. Most importantly, you’ll need to change some gearbox and differential lubricants more frequently. Be sure and check your owner’s manual for factory recommended service intervals.

Many late model vehicles have synthetic lubricants installed in these systems. As a result, these components often do not require a drain interval when operating under normal conditions. However, if water gets into the lubricant (i.e. a differential submerged under water when launching a boat) then the lubricant should be replaced immediately.

Manual Transmissions and Transaxles

While many older transmissions required the use of “GL” rated lubricants, this is not the case today. Many late-model manual transmissions and transaxles require unique gear lubricants that have been tailored to be used with their designs. For example, the NV 1500, NV 3500 and NV 5600 manual transmissions used in Dodge trucks require Mopar Manual Transmission Lubricant, part no. 04874464 meeting MS-9224.

Transfer Cases While many 4WD transfer cases in Jeep and Dodge trucks require automatic transmission fluid, such as Mopar ATF+4,® some late model AWD systems require special lubricants like Mopar Transfer Case Lubricant LX. This is a lubricant designed specifically for the AWD Chrysler 300, Dodge Charger and Dodge Magnum MS 140 transfer case.

Differentials

Most Chrysler LLC differential applications still call for the API GL-5 service rating. The owner’s manual will provide the correct SAE viscosity grade recommendation. It’s important to note that when replacing the lubricant in limited-slip differentials, a few ounces of friction-modifier additive be added with the gear lubricant for the differential clutches. Failure to use this additive will result in clutch chatter and shortened clutch life.

By following the appropriate maintenance schedule and making sure your vehicle has the appropriate factory gear and axle lubricants, you’ll help to ensure more years of service out of your drivetrain components.