AM-98-47 BASESTOCK VOLATILITY AND OIL CONSUMPTION

Description:

This study extends our initial report published last year on the effect of SAE 5W-30 Passenger Car Motor Oil (PCMO) volatility on engine oil consumption. The study expands the testing variables by including the effect of viscosity grade on oil consumption and by adding two additional vehicles to the testing program. The viscosity grade impact on oil consumption was determined to give approximately 4% reduction in oil consumption for every 1 cst increase in the kinematic viscosity @lOO “C. The combined oil consumption data from all three vehicles tested showed that on average, oil consumption decreases about 3% for every 1% reduction in either (I GCD %off @371 “C or Noack volatility of the engine oil. The data also suggestst hat both GCD and Noack volatility need to be decreasedin order to reduce the oil consumption at the expected rate. Overall, the correlation with oil consumption was better for GCD volatility than Noack volatility. The observed oil consumption reduction rate as a function of GCD volatility and kinematic viscosity agreed well with previous fleet test results by both Exxon and Sun. Finally, the current data suggests that an oil consumption reduction of 20% to 25% could be expected by changing the volatility specification of OW and SW-XX PCMOs from the current GF-2 specification limit to the preliminary proposed GF-3 specification.