If you think of advanced lubricants as something required to pass your ISO audit, then you’re missing out on some pretty amazing technology. Unless your shop’s rotating masses are using passive magnets, then you probably know the importance of selecting the best lubricants for your equipment. Next to diesel and gasoline, lubricants are the lifeblood of the automotive industry, so much so that the DOE is putting up 11.6 million dollars of taxpayer money to fund the development of lubricants for combustion engines that achieve 2% in fuel economy. Anyone who has had their eyes open for the last 30 years can attest to the technological advances in virtually everything. So it’s no surprise that lubricants have become very specialized, application-driven, and highly engineered products. So let’s start with the basics: almost every oil currently in use can be broken down into five base oils, as specified by the American Petroleum Institute (API 1509, Appendix E). Group I, II, and III of API’s base oil categories comprise all oils refined from petroleum. Group IV covers full synthetic (polyalphaolefin) oils. Group VI is classified as other oils; this is where the really cutting edge materials technology lives. The API creates very comprehensive standards, so I’ll summarize groups I through IV in simple terms before digging into group V.Group I base oils have a viscosity index range of 80 to 120 and are designed for operating temperatures of 32 to 150°F. The refining process is also simple, which makes Group I oils the least expensive.
Group II base oils are similar in price to Group I, with the same viscosity range; however, Group II is refined using hydrocracking (pressure & heat). This gives it better antioxidation properties.
Group III oils have a viscosity index greater than 120; they are also hydrocracked but at an even higher pressure and temperature. The added refining increases cost, but it also produces a more pure base. Even though Group III oils are refined from crude oil, they can be referred to as-synthesized hydrocarbons.
Group IV oils are composed of polyalphaolefins (PAOs), which comprise a number of synthetic lubricants. Because Group IV oils are synthesized, they are engineered for use in applications with extreme heat and cold, and with a wider range of viscosity.
Group V base oils are the most diverse and include silicone, phosphate ester, polyalkylene glycol (PAG), polyolester, biolubes, and others. The category also contains base oils that may be mixed with other bases to produce specific properties. Silicone oils are used in everything from food products to insulation and dampening applications, while polyolester oil or “POE” is primarily used in refrigeration compressors. Phosphate ester oil is very popular for applications such as electrohydraulic control (EHC) system in steam turbines or for electrical power generation. This is a high-performance oil, and as such it has good and bad characteristics. It has excellent lubrication properties and exhibits stability in the presence of water. However, it’s also hard on some elastomers and requires a great deal of monitoring and management.
Biolubes represent one of the fastest-growing lubrication markets. The global bio-based lubricants market was worth 1.7 billion USD million in 2011 and is expected to reach 2.4 billion USD by 2017. Part of that growth is due in part to one of the most diverse in this group of base oils, polyalkylene glycol (PAG), which has been in use for over 50 years in applications such as hydraulic fluids, metalworking fluids, lubricant, and as a fuel additive. The new generation of PAG based oils, such as those manufactured by DOW, are outperforming petroleum-based products while being fire resistant and green. PAGs deliver high viscosity, good low-temperature performance, excellent control of deposits, and hydraulic stability. Also, PAGs will not oxidize, and are non-varnishing; that means clean parts. Imagine rebuilding a gearbox or transmission without having to soak parts overnight in the parts washer. This family of polymers is finding its way into more and more applications, solving problems that conventional petroleum base oils have failed to. This trend represents the future of lubricants, and possibly the demise of hydrocarbon-based oils.
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