The Effect of Friction Modifiers and DI Package on Friction Reduction Potential of Next Generation Engine Oils: Part I Fresh Oils 2018-01-0933

Friction reduction in lubricated components through engine oil formulations has been investigated in the present work. Three different DI packages in combination with one friction modifier were blended in SAE 5 W-20 and SAE 0 W-16 viscosity grades. The friction performance of these oils was compared with GF-5 SAE 5 W-20 oil. A motored cranktrain assembly has been used to evaluate these, in which friction mean effective pressure (FMEP) as a function of engine speeds at different lubricant temperatures is measured. Results show that the choice of DI package plays a significant role in friction reduction. Results obtained from the mini-traction machine (MTM2) provide detailed information on traction coefficient in boundary, mixed and elastohydrodynamic (EHD) lubrication regimes. It has been shown that the results from the cranktrain rig are fairly consistent with those found in MTM2 tests for all the lubricants tested. Analytical studies suggest that the traction coefficient increase in mixed lubrication regime is associated with the lubricant starvation due to the tribofilm formation. Oil film thicknesses have been measured as a function of rolling speeds at various temperatures using EHD2 rig. Analytical study indicated that the observed higher oil film thickness at low speeds and high temperatures can be explained by surface roughening or plastic deformation of the surface.