Naphthenic oils, by comparison, are kept on the sidelines and seldom receive as much attention as paraffinics. Yet naphthenics play an important part in the industry, finding use in specific types of lubes that could not be manufactured as easily or readily using paraffinic oils.

Naphthenic base stocks are made from crude oils that contain relatively large proportions of naphthenes, or cyclical hydrocarbons, and small proportions of long chain hydrocarbons, or wax. Crudes found in areas such as Venezuela, the North Sea and Australia have as much as 50 percent or more naphthenic content and are therefore referred to as naphthenic. There are also small sources of naphthenic crudes in the United States, as well as finds in Russia and East Asia.

The biggest suppliers of naphthenic base stocks are Ergon and Calumet, which are headquartered in the U.S., and Nynas, which is based in Sweden but which also markets base stocks produced in the U.S. and the Netherland Antilles. While naphthenic producers generally operate on a smaller scale than major oil companies that make paraffinic base stocks, these companies are truly international in that they supply on a global basis through a chain of affiliates and distributors. Now these players are being rivaled by companies such as PetroChina and CNOOC that are making naphthenic base stocks in China from local crudes.

While paraffinic base stocks are divided into the API categories I, II and III, naphthenics are one of several types lumped into Group V. Costs for making naphthenic base stocks and Group I paraffinics are roughly equivalent, but naphthenics tend to be priced slightly higher. Since the naphthenic market has relatively few suppliers, it is possible for these producers to achieve higher netbacks.

Because they are produced in a small number of locations, naphthenic base stocks – and lubricants made from them – often incur additional costs for transportation, packing and handling. These costs are reflected in somewhat higher prices in export markets such as South Africa, India, South America and the Pacific Rim.

The molecular differences between naphthenics and paraffinics lead to differences in their performance characteristics. Naphthenics, because they have higher numbers of both cyclical and aromatic hydrocarbons, have better solubility, meaning they do a better job of dissolving chemical additives. On the other hand, the higher levels of cyclicals and aromatics mean naphthenics also have poorer oxidative stability.

Naphthenic oils are used in the production of many different finished products, with the lighter 8 to10 centiStoke grades going to items such as electrical transformer oils. Materials such as refrigeration oils and metalworking fluids, where the lubricant is added to water to form an emulsion, are other areas where naphthenics come into their own.

Many grease manufacturers around the world depend on naphthenics, using grades with viscosities of 500 to 700 Saybolt Universal Seconds as primary ingredients in their products. Heavier cuts – around 2,000 SUS – are used within the rubber industry in the manufacture of things like tires, hoses and insulation. Other naphthenic applications include process oils, printing inks and adhesives. Plainly there is a long list of everyday goods which would be more difficult to produce were it not for the availability of naphthenic base oils.

One refiner claims to have succeeded in making a naphthenic bright stock. Bright stocks are extra-heavy cuts popular as ingredients in finished lubes such as marine cylinder oils and some heavy-duty diesel engine oils. Until now, bright stocks have been produced only by Group I plants, and their supply has diminished with the closure of many Group I facilities. Presumably naphthenic bright stock would be in high demand.

Valentina Serra-Holm, Nynas marketing manager for the lubricants industry, says naphthenics have a sunny outlook, especially with the advent of Group II and Group III oils. Because those grades have greater oxidative stability but less solubility than Group Is, the distinction between naphthenics and the paraffinic side of the market is increasing. Serra-Holm, who helped provide background information for this column, contends that this will increase demand for naphthenic base stocks in applications that value their strengths. In addition, some predict naphthenics will become popular as blend stocks used in combination with Group III oils to help provide some of the solubility that the latter lack.

With more sources of naphthenic crudes being identified in regions such as Brazil, Russia and China, naphthenic refiners should have no trouble securing the feedstocks they need to maintain outputs. From all angles it appears that naphthenics will continue to deserve attention from the baseoil market.