A viscosity modifier solution to reconcile fuel economy and durability in diesel engines

Abstract In this paper the design and architectural features of a new viscosity modifier (VM) with the optimal balance between fuel economy and durability are explored. The viscometric properties of the new VM and fuel economy performance are described and demonstrated in a range of diesel engines, both in passenger vehicles in the New European Driving Cycle (NEDC) and in a mid-size diesel engine under a variety of heavy duty driving conditions. In both FE tests, up to 2% fuel economy improvements were consistently observed for the lubricant oils formulated with the new FE VM. In addition, the durability in sooted environment is addressed which is now critical for both passenger car and heavy duty diesel oils, and the VM׳s role in soot-induced viscosity increase as related to both retained fuel efficiency and soot-induced wear is demonstrated. The new VM delivers additional control of soot-induced viscosity control in bench screening tests, where the oil viscosity was reduced by an order of magnitude at 9% soot loading condition. Furthermore, in both Peugeot DV6 and Mack T11 tests the kinematic viscosity of the highly sooted oils was reduced by more than 50% at the end of the tests after replacing the conventional VM with the new FE VM. Lastly, wear and durability performance is demonstrated in both engine screening tests and heavy duty engine tests, where the new FE VM helps maintain the low soot-induced wear and the outstanding engine cleanliness.