Originally Posted By: XPR
Thats the popular claim, although no one has manged to point to any test that shows it has any effect.
From the 2004 paper "Overview of EU Oil Quality and Emissions Legislation Developments" by Mike McCabe and Alison Fisher of Lubrizol Limited
Quote:
Emissions
The third factor influencing changes in engine lubricant requirements is the continuing move to reduce the potentially harmful exhaust emissions generated by vehicles. European Union legislation defines the maximum permissible emissions of a range of substances. The dramatic reduction in permissible emissions that Euro 4 introduces is resulting in vehicle manufacturers
developing new engine and aftertreatment systems that are, in turn, bringing new performance demands for engine lubricants.
Some vehicle manufacturers are beginning to set limits on the levels of Sulphated Ash, Phosphorus and Sulphur which are significantly lower than the levels seen in existing engine lubricants. As Sulphated Ash, Phosphorus and Sulphur relate to some of the most fundamental building blocks of engine lubricant
formulations, reductions in these are resulting in the development of new technology for additives and may restrict the types of base oils used to formulate engine lubricants.
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CONCLUSIONS – THE IMPACT OF TRENDS ON ENGINE LUBRICANT FORMULATION
Impact of lower sulphated ash
Lowering the sulphated ash of a lubricant impacts the level of metal-containing detergents that can be used. Therefore, the detergency needs to be compensated with alternative detergent and dispersant technology.
Impact of lower phosphorus
The key lubricant component that contains phosphorus is zinc dialkyl dithio phosphate (ZDDP). ZDDP has been used since the 1950s as a very effective antiwear and antioxidation additive. As the levels of phosphorus are reduced to avoid poisoning effects on catalysts, ZDDP will need to reduced and replaced with
alternative phosphorous-free antiwear and antioxidant technology.
Impact of lower sulphur
ZDDP also contains sulphur and whilst level of sulphur in the engine lubricant will reduced as the level of ZDDP is reduced main contributor to sulphur is the lubricant basestock. API Group I basestocks can contain between 0.2%wt and 1.0%wt sulphur. Consequently, in lower sulphur lubricants the mineral basestocks will need be replaced by sulphur-free basestocks, as API Group III and Group IV. The majority viscosity modifiers contain mineral basestocks which will also be replaced sulphur-free basestocks. Some detergents also contain sulphur these will need to be kept to a minimum replaced with sulphur-free detergent chemistries.
Impact of trends on engine oil formulations
The move to aftertreatment system compatible engine lubricant technology represents a significant change in additive and lubricant formulating. New lubricant specifications are beginning to be introduced that restrict the level of sulphated ash, phosphorus and sulphur level and extensive research and investment is underway to develop and bring new chemistries to production. The challenge for the lubricants industry is to provide the fuel economy and extended drain benefits while formulating aftertreatment compatible engine lubricants with lower levels of sulphated ash, phosphorus and sulphur.
