Guntram Lechner, Alexander Knafl, and Dennis Assanis
University of Michigan
Spyros I. Tseregounis, Michael L. McMillan, Simon C. Tung, and Patricia A. Mulawa
General Motors R&D and Planning, Chemical & Environmental Sciences Laboratory
Ewa Bardasz and Susan Cowling
The Lubrizol Corporation

The effects of lubricating oil on friction and engine-out emissions in a light-duty 2.2L compression ignition direct injection (CIDI) engine were investigated. A matrix of test oils varying in viscosity (SAE 5W-20 to 10W-40), friction modifier (FM) level and chemistry (MoDTC and organic FM), and basestock chemistry (mineral and synthetic) was investigated. Tests were run in an engine dynamometer according to a simulated, steady state FTP-75 procedure. Low viscosity oils and high levels of organic FM showed benefits in terms of fuel economy, but there were no significant effects observed with the oils with low MoDTC concentration on engine friction run in this program.

No significant oil effects were observed on the gaseous emissions of the engine. PM emissions were analyzed for organic solubles and insolubles. The organic soluble fraction was further analyzed for the oil and fuel soluble portions. The oil fraction of the PM emissions was found to account for approximately half of the total PM emissions for the simulated FTP-75 test. Synthetic oils showed lower oil concentrations in the soluble organic fraction (SOF). Lower viscosity oils yielded less lubricating oil in the SOF than high viscosity ones, but the total PM was the lowest for the SAE 5W-30 oil. The concentration of unburned fuel in SOF was found to be lower for mineral oils. For a few PM samples analysis for the presence of toxics was performed and the results are discussed.