There is a trend with driveline lubricants toward improved thermal stability, vehicle component durability and fuel efficiency. These improvements can significantly reduce vehicle operating costs and improve customer satisfaction. Of these improvements, the fuel efficiency is getting a substantial attention due to recent focus on $CO_2$ emission control in Europe, Japan and $CAF{\'{E}}$ requirement in U.S.A. Lower viscosity axle oils and transmission fluids are currently being evaluated as potential solutions since these lubricants tend to reduce the churning losses and can improve the fuel efficiency. However, these lubricants should provide adequate gear and bearing protection, while increasing the overall efficiency of the driveline components. In this paper, the development of new fuel efficient axle was discussed with the focus on the effect of base oils, additives, and viscosity modifiers on the fuel efficiency of driveline components.

Significant changes in the performance requirements of finished lubricants is having a pronounced impact on the quality and manufacturing approach for base stocks, the building block for these products. Separation processing is no longer capable of producing high yields of premium base stocks and is rapidly being replaced with hydroprocessing. Isoparaffins are the most desirable component because of their high Viscosity Index, low pour point and excellent stability. This paper will discuss industry trends and the drive towards higher quality base stocks. Manufacturing options are discussed and examples presented to demonstrate the performance of these premium base stocks.