| abstract |
A molybdenum-free lubricating oil composition exhibiting improved fuel economy and fuel economy retention properties, which comprises: (a) a base stock oil compound of at least 50 wt.% mineral oil, the base stock oil having a viscosity of 4.0 - 5.5 mm2/s at 100 °C, 95 wt.% or more saturates, 25 wt.% or less napthenics, a NOACK volatility of 15.9 % or less, a kV of 4.0 - 5.5 mm2/s at 100 °C and a viscosity index of at least 120; (b) at least one calcium detergent and (c) at least one organic friction modifier, wherein the composition has a NOACK volatility of about 15 wt.% or less and contains from about 0.058 to 0.58 wt.% calcium from the calcium detergent. |