Fuel economy, Emission regulation and extended oil drain intervals (ODI) are the three key driving forces for engine oil development. More and more attentions have been focused on long ODI diesel engine oil both from the domestic OEMs and oil suppliers, and the ODI was being periodically improved from a normal mileage of about 1×104 kilometers to 6/8/10×104 km or even 12×104 km just within several years on China market. Lots and lots of factors may affect the oil life including oil properties, engine technologies, after-treatment devices and engine working conditions and so on. While from the oil side, the main factors contribute to the oil drain intervals may be the oil nitration and oxidation, soot contamination, base number deterioration and sludge accumulation and etc. There are two strategies to extend the oil longevity applied currently. One is the use of slow-release lubricant additives filters, in which the additives are incorporated into the oil filters, which slowly release it into the oil at elevated engine temperatures. The main additives used were Base Number (BN) promoters and anti-oxidation (AO) reinforcements. The other way is to improve the oil performance with elaborating formula technologies to provide support for extension of engine oil drain intervals. Use of super base stocks and advanced additive system specifically tailored for ODI ensures its excellent performance all through the service life. At drain intervals up to several times those normally recommended, excellent engine wear, good TBN retention, oil-thickening and sludge control have been demonstrated the extension of oil drain intervals has no significant negative impact on engine durability. An example of one such long oil-drain-interval oil is given.