Antioxidants are primarily used to prevent oxidative thickening of lubricants under demanding operating conditions. Further, antioxidants play a particularly important role in the reduction and control of deposit formation in both gasoline and diesel applications, said Ian Bell, senior research and development director at Afton Chemical Corp.

The demand for antioxidants will continue to increase over the next several years, agreed Aftons Research and Development Technical Director Chris Cleveland. Mainly, this is due to the increased performance demands that are expected from transmission fluids, including extended drain intervals, exposure to more severe driving conditions, higher average running temperatures and greater demand on the fluid as a cooling medium.

Longer-lasting lubricants requiring greater resistance to oxidative breakdown will play a large role in the growth of lubricant antioxidants. In terms of heavy-duty engine oils, the API CK-4 and FA-4 standards introduced in December 2016 required higher lubricant performance, including oxidation stability, noted Corinne Gangloff, marketing email and press release manager at The Freedonia Group.

Transmission fluids for dual clutch transmissions – which are forecast to reach up to 20 percent of the market through the next decade – will also contribute to the growth of the U.S. antioxidant market. Such fill-for-life applications require long-lasting lubricants with high oxidation stability.

The trend toward reduced levels of zinc dialkyldithiophosphate in engine oils will also boost demand for lubricant antioxidants.

ZDDP primarily acts as an antiwear additive, but also has antioxidant and anticorrosion properties. The chemical gained its popularity because of its multifunctional nature, allowing formulators to use less additives. Bell noted that ZDDP offers critical oxidation protection, acting primarily as a peroxide decomposer.

However, ZDDP has a detrimental effect on newer catalytic converters, with the zinc coating the catalyst and preventing proper treatment of exhaust. As a result, recent API engine oil service categories have limited the amount of ZDDP in engine oil, Gangloff explained.

As ZDDP levels are lowered, antioxidants will be needed to make up for the loss of its antioxidation capabilities.

Ben Sabol, brand and communication manager at the Lubrizol Corp., explained further: Many years ago phosphorus limits were imposed into engine oil specifications to protect original equipment manufacturers after treatment devices, which limits the treat rate of ZDDPs.

Some companies have already stopped using ZDDP in their formulations. Over the years, we have moved away from the use of ZDDP in ATF formulations for a couple of reasons. Firstly, it is incompatible with most clutch friction materials and can cause the chemical degradation of such materials. Secondly, the use of ZDDP contributes to an overall increase in fluid conductivity, which is detrimental to fluid performance in hybrid and eDrive transmissions, Aftons Cleveland said in an interview.

Afton, Chevron Oronite and Lubrizol dominate the U.S. additives market, but Freedonia was unable to give specific figures. The three biggest players hold a significant share of the antioxidant market due to their size and relationships with lubricant manufacturers, but overall the antioxidant market is more fragmented than other product segments, Gangloff told Lube Report.

Antioxidants do not have to be highly-specialized products and, as a result, are offered by a wide variety of companies, from large, multinational chemical companies to smaller, more specialized producers, she added.

Demand for all types of additives will grow 0.8 percent per year to 2.6 billion pounds over the next four years, according to the research firm. In a market characterized by a high level of maturity, lubricant additive suppliers can gain market share and sustain margins by partnering with original equipment manufacturers and lubricant blenders to match additive technology with performance needs and by significant investment in research, development and testing to meet lubricant specifications, Freedonia advised.