Concern at the amount of lubricants lost in the environment has prompted the search for environmentally considerate lubricants, i.e. lubricants which biodegrade as a result of the biological action of living organisms. Various test procedures and parameters are discussed, and the performance of various lubricants, including synthetics, is presented.

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A bacterium that was able to utilize Emkarate 1550 (E1550), a synthetic lubricant ester, as the sole source of carbon was isolated. The isolate was tentatively identified as Micrococcus roseus. The components of the E1550 ester, octanoate, decanoate, and 1,1,1-tris(hydroxymethyl)propane (TMP), were detected in the culture medium of cells growing on the ester. The TMP tertiary alcohol accumulated during growth and was not utilized by this isolate. The detection of the components of the ester in the supernatant of cultures indicated that one of the first steps in its degradation was cleavage of the ester bonds. Esterase activity was significantly

The chemical nature and technology of the main synthetic lubricant base fluids is described, covering polyalphaolefins, alkylated aromatics, gas-to-liquid (GTL) base fluids, polybutenes, aliphatic diesters, polyolesters, polyalkylene glycols or PAGs and phosphate esters. Other synthetic lubricant base oils such as the silicones, borate esters, perfluoroethers and polyphenylene ethers are considered to have restricted applications due to either high cost or performance limitations and are not considered here. Each of the main synthetic base fluids is described for their chemical and physical properties, manufacture and production, their chemistry, key properties, applications and their implications when used in the environment. IntroductionSynthetic lubricants have been available for many years; in the early 1930s, synthetic hydrocarbon and ester technologies were simultaneously developed in Germany and the United States. Development of a catalytic polymerisation process of olefins in the United States led to the formulation of automotive crankcase lubricants with improved low-temperature performance [1, 2]. These products were not commercialised due both to the inherent cost of these new synthetic base fluids and to performance improvements of mineral oil-based lubricants. In Germany, low-temperature performance drove the development of similar products [3], although the main objective was to overcome the general shortage of petroleum base stocks.Other than the special supply circumstances of the Second World War, synthetic lubricants were not commercially significant until after the war. In general, the improved properties of lubricants achieved with early synthetic base stocks could be obtained more cost effectively by improved formulations based on mineral oils. But the requirement for lubricants to perform over increasing temperature ranges, led by military and aero-engine performance, stimulated continuing development of synthetic lubricant technology. Synthetic lubricants are now found in all areas of 35 R.M. Mortier et al. (eds.), Chemistry and Technology of Lubricants, 3rd edn.,