F+L Week 2019 | Kien-Wee (Ben) Tan | Impact of viscosity index improvers (VII) on the formation of piston deposits in fuel economy engine oils
In recent years, the achievement of fuel economy through lower viscosity engine oils has been a topic of wide discussion among experts in the industry. Along this journey of engine oil evolution, new classes of viscosity index improver polymers have been constantly developed in order to meet the challenges arising from either hardware re-engineering, environmental protection or both.
While the fuel economy performance in an engine has been intensively investigated, little has been published on their durability aspects, such as cleanliness and piston deposits. In this paper, we will present on the no-harm test results of deposit formation, comparing between novel comb polymers versus conventional hydrocarbon viscosity modifier such as OCPs. The formation of coke like deposits has been studied on low viscosity engine oils in both engine and bench tests. The results of these fluids in the TDI engine test are compared against various screening tests such as micro coking test (MCT), panel coking test (PCT) and hot tube test (HTT).