Shen, X., Taribagil, R., Briggs, S., and Goldmints, I., "Next Generation Diblock Viscosity Modifier for Heavy Duty Diesel Engine Lubricants," SAE Technical Paper 2016-01-2315, 2016, doi:10.4271/2016-01-2315.
An unprecedented global focus on the environment and greenhouse gases has driven recent government regulations on automotive emissions across the globe. To achieve this improvement, Original Equipment Manufacturers (OEMs) have advocated a progressive move towards the use of low viscosity grade oils. However, the use of lower viscosity grades should not compromise engine durability or wear protection. Viscosity modifiers (VM) - polymeric additive components used to tailor the lubricant’s viscometric properties - have been viewed as a key enabler for achieving the desirable balance between fuel economy and engine durability performance. Self-assembling diblock copolymers represent a unique class of VMs, which deliver superior shear stability due to their tunable association/dissociation in the lubricating oil. Superior shear stability ensures that the oil viscosity and its ability to offer reliable engine protection from wear is retained over the life of the oil in the engine. In addition, some polystyrene containing diblock VMs can help to boost soot dispersancy due to polystyrene block adsorption onto the soot surface. This additional feature helps in preventing soot aggregation, thereby maintaining lubricant viscosity within desirable range and potentially reducing soot induced abrasive wear in the engine. Here we present a next generation diblock VM designed for high quality base stock applications and its performance attributes in top-tier heavy duty diesel (HDD) formulations. In particular, we demonstrate shear stability and soot dispersancy credits of this VM in bench, engine and field tests, as well as the ability to formulate low viscosity oils without compromising engine durability.