Oil 101: Understanding Gear Oils

Alright, so we know that an engine needs oil, of course, but so do transmissions, drivetrains, transfer cases, and differentials. However, your average motor oil is not going to cut it for these components; instead, they require gear oil. In this blog, we are going to focus more specifically on gear oils and how they’re different from regular motor oil. Welcome back to Gear Up with Gregg’s Propel Oil 101!

What is Gear Oil?

So, what is gear oil? Well, it’s a lubricant specifically made for transmissions, transfer cases, and differentials in machinery, cars, and trucks. Overall, motor oils and gear oils have some commonalities: they both lubricate, they both consider viscosity incredibly important, they have additives, and they cool and protect. But gear oils take additives much more seriously. Due to the fact that gear oils can be placed under extreme amounts of pressure, EP additives are more common. Motor oils can contain EP additives, too, along with a plethora of other additives, but you already knew that from our Oil Chemistry segment. Gear oils often also have rust and oxidation inhibitors, as many of the components found in drivetrains contain ferrous material that can become damaged if exposed to corrosion.

Benefits of Using Gear Lubricants

Besides lubrication, gear oil also aids in shock-loading and noise reduction. Shock-loading gears refers to when the gear train is suddenly forced to start or stop turning, or when a heavy load is applied to those rotating gears. The combination of viscosity and EP additives in gear oil allows for better lubrication in those tight gearboxes, which in turn, quiets the noisy components and allows for smoother rotation. Also, gear oil must provide greater protection against emulsification and foaming, as the motion of the gears tends to churn the lubricant, therefore, creating air bubbles that can cause damage to those intricate components.

Understanding GL-Ratings

Nowadays, there is a wide variety of gear lubricants, so how do you pick which gear lubricant is best for your application? Well, that will be determined by the conditions it has to operate under and its GL(Gear Lubricant) rating. The GL-rating refers to a gear lube’s ability to withstand pressure without any metal-to-metal contact occurring between parts, so the higher the pressure, the higher the GL-rating will be. There are four main classifications from the American Petroleum Institute (API): GL-1, GL-4, GL-5, and MT-1.

GL-1

GL-1 rated oils are used for manual transmissions that operate under mild pressure conditions. GL-1 indicates that untreated oil may be used without causing harm or additional wear to your gears. Oxidation and rust inhibitors, defoamers, and pour depressants may be used to improve the characteristics of the gear oil. However, friction modifiers and EP additives are not used in this rating.

GL-4

GL-4 gear oils are rated for use in spiral-bevel and hypoid gears in automotive axles operating under moderate speeds and loads. These oils have a moderate level of extreme pressure additives.

GL-5

Meanwhile, the GL-5 rating is designated for gears, particularly hypoids, in automotive axles under high-torque conditions at either low or high speeds. These oils have almost twice the amount of extreme pressure additives as the GL-4 rated oils.

MT-1

Finally, MT-1 oils are intended for non-synchronized manual transmissions primarily used in buses and heavy-duty trucks. Lubricants rated as MT-1 provide a particular level of protection against a combination of thermal degradation, component wear, and oil seal deterioration. All of which is not provided by lubricants in the GL-4 and GL-5 ratings.

These are important classifications for the transportation sector, and your vehicle’s manual should indicate which one is most suitable. And remember, just like how your car requires a specific viscosity of motor oil, all your other components require a specific GL-rating.

Propel Lubricants: Gear Oil Offerings

Now, let’s see what Propel has to offer us in their line of gear oils.

GL-5 Conventional Gear Oil

Oil 101: Understanding Gear Oils | Gear Up With Gregg's Blog

First is Propel’s GL-5 gear oil. This conventional gear oil has been formulated for multi-purpose, extreme-pressure applications such as gearboxes, manual transmissions, hypoid gears, and limited-slip rear axles. It also features thermal stability, corrosion inhibitors, and anti-wear and anti-friction agents, just to name a few. This gear oil is available in 1L, 20L, or 208L volumes, with an 80W90 grade.

Full Synthetic GL-5 Gear Oil

Propel also offers a full synthetic GL-5 gear oil. Since this is a full synthetic oil, it features high-quality paraffinic lubricating oils and some of the most technologically advanced additives, like oxidation and corrosion inhibitors, along with EP, anti-wear, and anti-friction agents. It also boasts superior protection against wear, especially in EP and high torque applications. This gear oil is available in 75W90 or 75W140 grades, and you have 1L, 20L, or 208L volume options to choose from. If you’re looking for some serious high-quality gear oil, your search stops here.

ISO Viscosity Grade Gear Oils

So, we mentioned GL-rated gear oils, but there’s another classification system we need to mention, which is ISO Viscosity Grade gear oil. The International Standardization Organization (ISO) established a viscosity grading (VG) system for industrial gear oils. According to the system, industrial gear oils are designated by the letters ISO followed by a number equal to the oil viscosity measured in centistokes at 40°C (104°F). The thicker the oil (the slower the flow rate), the higher the ISO VG number will be.

Propel offers a range of ISO industrial gear oils. These gear oils are available in 20L pails or 208L drums, with grades ranging from ISO 68 EP to ISO 320 EP. They are formulated to help lower friction, reduce wear, build a barrier, and control costs for spur, helical, bevel, and worm gear configurations. These gear oils also continue to perform well at high temperatures, in harsh conditions, and in the presence of water.

Propel Lubricants: Transmission Fluids Offerings

Now, both gear oils and transmission oils share some similar characteristics. But when it comes to transmission fluids more specifically, Propel has a good selection you can choose from.

Standard Automatic Transmission Fluid

First is the standard automatic transmission fluid. It is a reliable go-to for older transmissions, including those asking for Dex II automotive transmission fluid.

Multi-Vehicle Low Viscosity Automatic Transmission Fluid

Next, we have the Propel synthetic multi-vehicle low viscosity automatic transmission fluid. An important note for this transmission fluid is that it has been approved for use in applications calling for Dexron VI and Ford Mercon LV. The list of OEM specs this product caters to is extensive, so make sure you pull out your Propel brochure to really appreciate the broad coverage this product provides. If you are looking for a single high-performance product to cover the demands of a mixed fleet, this is the transmission fluid for you!

Full Synthetic Transmission Fluid

After that, we have Propel’s full synthetic transmission fluid. This transmission fluid is both strong and durable, so you know that the performance will be top-notch for your common HD applications.

Full Synthetic Heavy-duty Automatic Transmission Fluid

And finally, we have Propel’s full synthetic heavy-duty automatic transmission fluid. Formulated specifically for HD applications like HD trucks or bus transmissions, this transmission fluid can truly stand up against some of the most severe operating conditions and extended drain intervals, even in applications that need to meet the Alisson TES Z95 spec.

Next time on Propel Oil 101, we are going to cover Hydraulic Oils, and Propel lubricants will be back once more to help us conclude this video series. If you’ve liked what you’ve learned so far, why not subscribe to our YouTube channel? You can find the video that goes along with this blog on there! If you have any questions, you can give us a call! See you in our next Propel Oil 101 blog!