Demonstration of Fuel Economy Benefit of Friction Modifier Additives via Fuel-to-Lubricant Transfer in Euro-5 Gasoline Fleet

Improved fuel economy is a key measure of performance in the automotive industry, driven both by market demand and increasingly stringent government emissions regulations. In this climate, targeting even small benefits to fuel consumption (FC) can have a large impact when considering fleet average CO₂ emissions. Lubricant properties over the course of an oil drain interval (ODI) directly influence long-term fuel consumption. Furthermore, viscosity control gasoline additives have been shown to provide FC benefit via fuel-to-lubricant transfer. This study investigated whether consistently fueling with gasoline containing friction modifier (FM) additives could provide a long-term fuel consumption benefit via a lubricant transfer mechanism.

A robust fleet trial method was employed to quantify fuel consumption benefits of two friction modifier additive packages relative to a baseline deposit control additive (DCA) package in a 95 RON, E5 fuel. FC was measured for 32 market relevant vehicles over the course of a European ODI. The test was performed with 12,000 mile on-road accumulation in a 60/40 urban/high speed driving route. Changes in FC were measured periodically on a chassis dynamometer (CD) using the industry standard New European Drive Cycle (NEDC) procedure. NEDC emissions results demonstrated statistically significant FC benefits for fuels containing FM additives relative to a DCA only reference fuel, with 0.60% and 0.71% benefit at the 95% confidence level. Lubricant analysis confirmed transfer of FM additives to the lubricant sump, providing support for a fuel-lubricant interaction mechanism. This study thus demonstrates that statistically significant long-term fuel consumption benefits can be obtained by consistent fueling with FM dosed gasoline.