What is Moly?

What is Moly?

Molybdenum Disulfide, simply known as Moly, is used both independently as a dry lubricant and as an additive in lubricating greases. Dry lubricants reduce friction between two sliding surfaces without the need for an oil medium. Dry lubricant molecules have a natural attraction to metal and adhere themselves to metal surfaces. These molecules create a layer of protection that prevents wear and tear as well as significantly improve lubricity of metallic surfaces.

How Does Moly Work?

When used on its own, Moly is impregnated into the surfaces of metal parts to improve the lubricity and protect the parts themselves. When used in greases and lubricants, the Moly attracts itself to the metal surfaces as an anti-wear surface coating. When used in lubricants, Moly’s efficacy is limited if the additive remains suspended. It is important to ensure that the Moly is compatible with the oil or grease. If it is not compatible, the compounds could drop out and plug oil passages and filters.

Moly has a variety of unique properties that distinguish itself from other solid lubricants and solid additives. These include:

  • An inherently low coefficient of friction
  • Strong affinity for metallic surfaces
  • Film forming structure
  • Stability in the presence of most solvents
  • Effective lubricating properties from cryogenic temperatures to 350 C in air
  • Efficacy in vacuum and aerospace applications

Moly Greases

Moly greases can have concentrations from anywhere from 1 to 20%. Typically, Moly greases typically contain 3 to 5% Moly. Moly greases are generally used in operations where high pressure metal surfaces are sliding against each other. These include roller bearings that have very heavy loads and shock loading. Moly greases are also recommended in slow or oscillating motion that is used in universal and CV joints. Moly greases used in high-speed bearings can create problems such as “skidding,” where a bearing roller fails to rotate a full 360 degrees.

Due to its lubricating abilities in vacuums, Moly and Moly greases are popular in aerospace applications. Temperature limitations for Moly are much higher in space (1200 C compared to 350 C in air) thus can withstand extreme temperatures in space. Moly is used for low speed systems such as solar array drives, sensors, and antenna scanners.


As a solid lubricant, Molybdenum disulfide (Moly) serves as a better lubricant and additive than graphite because of its ability to operate under very heavy loads and in vacuum environments. If your machine’s manual calls for a moly grease, it is important to ensure a moly grease is used and the moly grease is compatible with other lubricants in your equipment.

What are Lubricant Detergents?

Detergents Defined

Detergent additives perform two key functions. Like household detergents, the additives keep metal components clean and free of deposits. Additionally, detergents neutralize acids that form in the oil. This is key for systems where component cleanliness is essential. Originally developed for engine oils, detergents addressed carburetor deposits that could hamper performance. Detergent additives were also found effective in fuel injectors. The detergents reduced deposits that affected fuel spray patterns.

How do Detergents Work?

Detergent additives are basic in nature, thus serve as a neutralizer for acidic contaminants that may arise in your lubricant. In the past, these detergents were barium-based, however modern chemistry has allowed manufacturers to move to different formulations. Today, most additives use either calcium-based chemistry or magnesium-based chemistry. As an oil is subjected to oxidation, it will start to collect acids. As these acids build up, the oil’s Total Acid Number (TAN) will increase. The basic and alkaline detergent will neutralize the acids and reduce the TAN. However, as the detergent is used, the Total Base Number (TBN) will decrease to point where the oil will need to be replaced. Therefore, measuring TBN is crucial to engine performance and lubricant effectiveness.

In high-temperature applications, metal compounds leave an ash deposit when burned. This residue buildup requires many OEMs to require low-ash oils. Detergent additives are used to clean these deposits. However, dispersants are included as well to help clean the engine. Dispersants are used to keep engine soot particles suspended and prevent agglomeration (forming larger soot deposits). The dispersant and detergent work together to suspend contaminants and neutralize acids. Eventually, the additive capacity will exceed its limit and require users to change the oil and replenish the additives.

Detergent v. Non-Detergent Oil

How do you know if you need a lubricant with detergent additives? Usually, an OEM will specify whether the equipment needs a detergent oil or non-detergent oil. Applications that could face high levels of water and contamination are good fits for detergent oil. Some examples include: off-road equipment, marine equipment, trucks & fleets, and many more. The high levels of contamination need to be neutralized with dispersants in order to keep pumps and valves clean and running.

Sometimes, OEMs require oils to not have detergent additives. Some manufacturers will produce special Non-Detergent oil to meet these specifications since, most oils now have detergent additives for better performance. Non-detergent oils are used in bearings and chains in non-critical once-through systems. It is also recommended for gas-powered appliances such as lawnmowers and tractors. Some non-detergent oils are not recommended for automotive gasoline engines (detergent oils are recommended).

Detergent Oil Today

With the developments in detergent and dispersant technology, most oils now have some sort of detergent additive to help combat high TANs and prevent sludge build-up. Even though non-detergent oil is still marketed today, it is only required for a few specific applications and not recommended by many OEMs. When selecting your lubricant, detergency is important to consider because high detergency will protect your parts, keep your system clean, and maximize performance. If you are using non-detergent oil, consider making the switch to an oil that has detergent additives.

Twin Specialties offers both detergent and non-detergent oils to meet your specifications and OEM requirements. We also offer a variety of motor oils and heavy duty engine oils with high-quality detergent additives to meet your specifications and budget. Contact us today for more information.