Castrol India Ltd. has launched Castrol Vecton RX Fuel Saver 10W-40 diesel engine oil, co-engineered by Tata Motors Ltd., and designed to increase fuel efficiency of Tata trucks by 3%. According to Castrol, Vecton RX Fuel Saver has the potential to save almost Rs 40,000 (USD 640) per year for a truck which travels 100,000 kilometers in a year.