Oil Thickening in the Mack T-7 Engine Test—Fuel Effects and the Influence of Lubricant Additives on Soot Aggregation 852126
For a diesel lubricant to meet the new Mack EO-K/2 specification, it must be effective in preventing excessive viscosity increase during the 150-hour Mack T-7 test. The severity of this test is shown to be highly dependent upon fuel chemistry and injection timing. A comparison of various lubricant formulations in the Mack T-7 engine run with a given fuel suggests that nitrogen-containing succinimide dispersants, dispersant viscosity improvers, and supplemental ash in the form of overbased sulfonate detergents are effective in controlling viscosity increase. Crankcase oil thickening follows a modified form of Brinkman’s equation and can be predicted from measured values of soot particle size and concentration. Basic lubricant additives are shown to prevent particle size growth by adsorption on to the acidic soot surface, thereby interrupting soot aggregation and retarding oil thickening.
Citation: Covitch, M., Humphrey, B., and Ripple, D., "Oil Thickening in the Mack T-7 Engine Test—Fuel Effects and the Influence of Lubricant Additives on Soot Aggregation," SAE Technical Paper 852126, 1985, https://doi.org/10.4271/852126. Download Citation
M. J. Covitch, B. K. Humphrey, D. E. Ripple
The Lubrizol Corp.
1985 SAE International Fall Fuels and Lubricants Meeting and Exhibition
Engine Lubrication-SP-0640, SAE 1986 Transactions - Fuels and Lubricants-V94-7