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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.

Harsh emission control regulation restricted the sulfated ash, sulfur and phosphorus (SAPS) level in passenger car motor oil (PCMO), thus lubricant industry need to find new additive to partially or wholly replace Zinc dialkyldithiophosphate (ZDDP), which has been used as an antioxidant and anti-wear agent for several decades. Overbased crystalline calcium sulfonate (CCS) detergent comprises calcite calcium carbonate and this structure might be useful to improve the anti-wear property of engine oil in severe lubrication condition, especially for PCMO with lower SAPS level. Frictional characteristics were studied between overbased amorphous calcium sulfonate (ACS) detergent and CCS and their interactions with dispersant and ZDDP by Mini-Traction Machine, which is often used to measure the Stribeck Curve of lubricant.