As the lubricant industry seeks to optimise the production of top-quality products, there is a growing demand to incorporate inherently unstable, cracked, and highly olefinic components into petroleum products.

Adding these components can result in undesirable product characteristics, like darkening, gum formation, and reduced induction periods. The presence of fuel antioxidants can help balance highly olefinic materials, mitigating these issues.

What is the Role of Antioxidants?

Antioxidants are designed to extend the storage life of oils and greases by enhancing resistance to oxidation. They also serve as oxidation inhibitors in most petroleum products. Antioxidants also reduce excessive gum formation, which is the primary cause of fuel-filter plugging and poor combustion, meaning pistons and injectors are not used to their full capacity.

Notably, the addition of these additives allows lubricants to perform at higher temperature levels than they would without them. Most synthetic lubricants, particularly those made of hydrocarbons, are highly vulnerable to oxidation.

Oxidation is a continuous process initiated by forming interactive peroxides and free radicals, causing oil thickening in most applications. Destructive oxidation occurs in a three-step process: initiation, propagation, and termination.

The initial stage involves the formation of a free radical, a highly reactive species which can interact with oxygen to generate a peroxide radical, forming additional free radicals. The propagation stage causes further decomposition of the components of the lubricant. The last termination process involves the formation of a stable compound by removing free radicals from the system.

This is a continuous cycle; unless it’s broken, oxidation will not stop until the lubricating oils and greases are unusable. Ultimately, the role of antioxidants is to interact with free radicals to form stable species and interrupt the degradation process.

Types of Antioxidants

Fuel antioxidants are classified into two major groups by their mechanism: The first type is the primary antioxidants which mop up and react with the free radicals during the propagation phase. These are typically aromatic amines and hindered phenolics.

Secondary antioxidants interact with reactive peroxides, including phosphites and some sulfur-rich compounds like thioesters and thioethers. These types of antioxidants perform different functions to mitigate oxidation and are responsible for terminating the cycle to prevent further propagation.

In most cases, petroleum products will use both the primary and secondary antioxidant additives to optimise the performance of the lubricant and promote oxidative stability. Thus, obtaining the right combination of oxidants is always vital to the lubricant’s functioning.

Contact Bisley & Company

Bisley & Company introduces Bislube, a class of additives used in different application areas in the lubricant industry. These additives include pressure friction modifiers, antioxidants and corrosion inhibitors. These additives can be found on the Bisley International website, and coming soon to the Bisley & Co website. Bislube Antioxidants, such as BODPA and DND are available as they are the major antioxidants for the general purpose of petroleum products.

Please browse our website to learn more about our newly launched antioxidants. And don’t hesitate to contact our experts if you have any questions or concerns.