Synthetics basics: Polyalphaolefins — base fluids for high‐performance lubricants

Abstract

AbstractPolyalphaolefins or PAOs are saturated oligomers manufactured via the catalytic oligomerisation of alphaolefins. An oligomeric mixture is obtained which is then hydrogenated and distilled to produce a range of PAOs. These synthetic fluids are differentiated and graded by their viscosities at 100°C. PAOs are mainly used as high‐performance functional base fluids in engine lubricants, gear oils, hydraulic oils, automatic transmission oils, compressor/pump oils, and greases.Automotive engine (crankcase) lubricants represent the biggest market for PAOs and here they compete with petroleum‐based oils. When compared to mineral oils, PAOs exhibit a number of inherently superior physical and chemical properties, such as greater fluidity at low temperature, lower volatility, a higher viscosity index, a lower pour point, better oxidative/thermal stability, low toxicity, and biodegradable low viscosity grades.This combination of properties means that PAOs enhance the formulator's ability to produce high‐performance lubricant oils. Some examples of performance benefits obtained from PAO‐based formulations have been shown to match and even exceed the performance of higher cost traditional ester‐based oils when tested under the new Japanese Automobile Standards Organisation (JASO) FC two‐stroke specifications. Low viscosity automotive engine oils, which can only be formulated with PAOs, can produce a fuel saving of >2% when tested under US Federal Test Procedure (USFTP) 75.