Site Information

 Loading... Please wait...
Free Shipping on orders $75+ (Click for details)
Navigation Tools
The Flight Blog Logo

Aviation Grease: A Critical Component for Maintaining Airworthiness

Posted by Sarah Simonovich on

You might say that grease is the unsung hero of the aviation world. Sure, fuels and engine oils get you up in the air (and pilot skills keep you up), but it's the lubricants that help keep everything running smoothly.  
Using grease is important for keeping your plane in perfect flying order. But what exactly are aviation greases?  
Greases are either solid or semi-solid lubricants meant to protect, seal, and lubricate aircraft components. As with any type of lubricant, the goal is to reduce friction by creating a film that separates moving surfaces. Lubricants, including greases, prevent metal-to-metal contact.

While grease can behave similarly to lubricating oils when used as a lubricant, they are not the exact same thing. Greases are not simply very viscous (or thick) oils. In fact, grease is used when oils cannot provide sufficient lubrication. What makes grease different is it contains an additional thickener which gives it its solid or semi-solid consistency. This consistency allows the grease to stay put and not settle. 

There are three major components to the composition of grease: the base oil, thickeners, and additives. There are many grease applications in the aviation industry and just as many grease formulations to meet those requirements. All three of these component categories determine whether a specific grease is ideal for any given application.

Base Oil

As with any oil or lubricant, the base oil is the most important factor in determining what grease is right for you-and your plane. It is actually the oil that carries out the actual lubrication, and not the grease itself. The application will determine what base oil is best-synthetic or mineral-and what viscosity. For example, a high viscosity mineral oil would perform well in applications involving heavy load conditions. However, a high viscosity mineral oil wouldn't be ideal for low-temperature applications because they can become too thick.

Synthetic-based greases are more often than not better for performance over a very wide temperature range. While mineral oils are derived from petroleum, synthetics are often derived from esters. Only use the type of base oil as specified by your aircraft-synthetic oils can be more aggressive to seals.


The thickening agents impact your grease's consistency-its softness or stiffness. Grease can range from very soft (cream-like) to very stiff and solid (wax-like). A grease's ability to resist changing consistency despite heavy working conditions is referred to as -Working Stability,- quantified by measuring penetration value, often referred to as -Working Penetration- value. Aviation greases typically have worked penetration values of around 260-320. 

The thickeners don't actually perform any lubrication, but they do act like a sponge. When stress or pressure is applied, oil is released to provide lubrication. When the stress is released, the thickener and oil return to their semi-solid or solid state.

Thickening agents can generally be classified as soap-based or non-soap-based. Soap-based greases include aluminum, calcium, sodium, or lithium soaps. A -soap- is a salt formed when a metal hydroxide, or alkali, is reacted with a fatty acid. Non-soap-based include silica gel, clay, and substituted urea, with clay being the most common.

Each type of thickener has its own benefits and limits depending on the application.


The additives found within aviation greases are similar to those used in lubricating oils. These can include anti oxidants, corrosion inhibitors, load carrying additives, extreme pressure additives, etc. They are incorporated into both the base oil and the thickener. One thing to consider with additives is that while certain ones can provide considerable advantages in one application can also be detrimental in another. Take tackiness additives, for instance, which are common in greases. These additives make a grease stringy and help it stay in place. These greases are great in applications that see a lot of jarring thrust loads--like Bucket Pins on a Backhoe or Universal Joints on a car--but you would not want to use that same grease on a high speed bearing application. A tacky grease would create too much internal friction causing the bearing to over-heat.

In short: all components of a grease must be considered before utilizing it in any part of your aircraft.

Looking for Aviation Grease?

Mobilgrease 28 is a wide-temperature, antiwear grease that combines the features of a PAO-based fluid with an organo-clay thickener. This multipurpose aviation grease can be used in landing wheel assemblies, control systems and actuators, screw jacks, servo devices, sealed-bearing motors, oscillating bearings, and helicopter rotor bearings on both military and civil aircraft. You can get your hands on this supreme grease at AviationOilOutlet.com.






View Comments

Why you can't fix your plane with just any parts

Routine certified aircraft maintenance is an important aspect of owning a plane. This makes owning an aircraft different from any motor vehicle. What really distinguishes plane maintenance, though, is the required use of FAA-approved parts. Various aircraft parts and materials may be "standard parts," which the FAA defines as "a part or material that conforms to [...]

Read More »

Airline Spotlight: Justice Prisoner & Alien Transportation System

After the tragic attacks in the U.S. on September 11, 2001, only one airline was allowed to continue flying in U.S. airspace that day. Justice Prisoner & Alien Transportation System (JPATS), nicknamed -Con Air,- is the largest prisoner transport network in the world.What is JPATS?Two air fleets joined together in 1995 to form JPATS-the Marshals [...]

Read More »

AeroShell Oil W100 vs W100 Plus

Fueling your aircraft requires choosing a premier oil that promotes engine health. For those who use  AeroShell's single-grade ashless dispersant engine oils, a common question is: what is the difference between AeroShell Oil W100 and W100 Plus?  In short, both single-grade ashless dispersant (AD) engine oils serve piston engines and help minimize sludge formation.W100 Plus contains the [...]

Read More »

When to Prime a Piston Aircraft Engine

We covered the basics of caring for a piston engine aircraft and how important it is to fly the aircraft regularly here. However, starting a carbureted engine in the cold or when it has not been used for a while is notoriously difficult.The key to successfully starting a carbureted engine in the cold is to find [...]

Read More »

How to Care for a Piston Engine Aircraft

Piston engines, or internal combustion engines, became prominent in the Wright brother's era. All aircraft was powered by a piston engine until the early 20th century when jet engines were introduced. They were even installed in steam engines and function similarly to automobile engines. Today, piston engines are generally for business and private use as they have [...]

Read More »

Foldable Airplane Wings May Be in Our Future

When it comes to flying, we all know the importance of aerodynamics-the better they are, the better the flight. Less fuel is used, and planes fly faster. NASA is beginning to test foldable wings to help improve flight performance even more.NASA Testing the Spanwise Adaptive WingFoldable wings have actually existed for some time, but the system [...]

Read More »

Pilot Cons: Flying Without a License

If online dating has taught us anything, it's that people lie. Some by using decades' old photos while others lie about where they live (or who they live with). It's not also that uncommon to find people lying about their credentials or work experience. There are some professions you would think would be harder to impersonate [...]

Read More »

State-of-the-Art Aircraft Maintenance: Why It's Essential & How Industry Leaders Do It Right

When it came to aviation supply chain services, maintenance used to be performed by the asset operator and original equipment manufacturers (OEMs). But as the aviation industry has felt the effects of the downturn in the global economy and changes in the political climate, the activity and cost of maintenance shifted to include optimized maintenance, [...]

Read More »

How to Become a Pilot: Here's What You Need to Know

If flying a plane has always been a dream of yours, you've come to the right place. At least as far as learning about becoming a pilot goes. There are a lot of requirements and training that goes into building the profession. We'll go over the foundation of these licenses in this post so you know [...]

Read More »

Recent Posts