The current trend within the automotive industry is aimed towards reducing the cost of vehicle ownership. A major area of focus is lengthening recommended vehicle service intervals. Automotive technology has now advanced to the point where, for many of today's vehicles, the first mechanical “tune-up” is not required until the vehicle has reached 100,000 miles. On the other hand, engine oil servicing is still recommended at intervals in the range of 3,000 to 7,500 miles in the North American market. Extension of oil change interval recommendations beyond 15,000 miles is now being discussed within the international automotive industry. This paper documents the development and testing of new synthetic engine oil technology under extended service intervals of up to 25,000 miles or three years. Exceptional performance has been demonstrated in industry standard North American (API) and European (ACEA) engine tests, as well as non-standard tests such as extended length engine tests, vehicle fuel economy retention tests, high mileage chassis rolls tests, and extended oil drain over-the-road vehicle tests under a wide range of driving conditions.