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Modern diesel fuels have changed substantially over the last few decades. Non-fossil fuel blend components are used and the composition of the fossil fuel components has significantly changed. Both these factors affect fuel solvency. It has previously been shown [1] that fuel solvency Impacts cold flow properties. Can be replicated using surrogate fuels. Surrogate fuels can be used to observe different cold flow additive effects. This paper illustrates how to apply these principles to develop additive technology to improve cold flow performance, using Korean fuels as an example. The approach can be applied to anticipate future fuel changes to optimise for the most economical performance.

Studies on cold flow performance have focused on the n-alkane wax precipitating from diesel fuel and their interaction with additives. Little attention has been paid to the solvent system of the fuel. There have been significant changes in the fuel solvent system, due to changes in refining processes and the use of first and second generation biofuels, as well as other components such as GTL. Understanding the extent of the impact of the fuel solvent system change, if and how the change effects wax precipitation, and whether the change influences additive wax interactions, will ultimately enable the optimisation of diesel fuel cold flow performance. This paper first describes a method to characterise diesel fuel solvency. The method is applied to sets of fuels to evaluate the changes in fuel composition over time. A method to replicate the variation in the fuel solvent system is described. The impact of changes in the solvent systems on cold flow properties is considered.

Low temperature pumpability is an important requirement for engine lubricants. It ensures that sufficient oil reaches the parts of the engine requiring wear protection on engine start-up. Until recently, most industry emphasis has been on the low temperature pumpability of the fresh oil. However, the oil can undergo a number of changes during its lifetime in the engine which adversely affect low temperature pumpability. Industry stakeholders are now expressing concerns about the potential risk of engine failures due to deterioration of low temperature pumpability of oils during their life cycle in the engine. Concerns have also been raised over the last few years that the move to Group III base stocks, while improving many of the properties of oil formulations, may also impact their retained low temperature pumpability.