Browse Publications Technical Papers 2021-01-1212

Evolution of the Additive Technology for Top Tier Lubricating Oils: Use of Calixarene Detergents for Fuel Economy Improvement 2021-01-1212

In view of CO2 reduction, aimed to mitigate global warming, Fuel Economy (FE) is gaining a primary role in new specifications for engine lubricating oils. Not only oil rheological properties and friction reducer additives, but also all the components of the formulation, such as basestocks, viscosity modifier and additive package, are involved in achieving FE performances.
Tribological tests were carried out in our labs to investigate the effect of detergent additives: in particular, the positive role of detergents based on Calcium salts ofcalixarenes, cyclic oligomers obtained from reaction of p-functionalized phenols with formaldehyde, emerged. This type of additives is particularly suitable for modern lubricants preserving aftertreatment efficiency as they are sulfur-free. In our labs both 400 TBN and 150 TBN Calcium calixarene-based detergents were synthetized and evaluated on MTM tribologicaltest where a lower friction coefficient is achieved in comparison to traditional detergents. Also the SRV tribological tests confirmed a positive effect of calixarenes detergents.
A preliminary engine test evaluation on Sequence VIE provided a further confirmation of the good behavior of calixarenes-based detergents jointly with an amino-type friction reducer: a FE result with a pass margin that amounts to one third of the ILSAC GF-6A limit for SAE 0W-20 (that is 3.8%) was achieved with the use of a fully calixarene-based detergent system.
The use of calixareneoverbased (OB) detergent in combination with neutral Calcium sulfonates, provided a slightly lower performance at Sequence VIE test. In M111FE tests, the SAE 0W-20 oil provided over 4% FE improvement, clearly higher than the ACEA C5 limit (that is 3%), while both 5W-30 at low (2.9 mPa.s) and high (3.5 mPa.s) HTHS viscosity fulfilled the ACEA C2 limit of 2.5%.
The same oils showed robust FE performances on chassis-dyno tests according to NEDC cycle where the candidate oils 0W-20 and 5W-30 almost doubled, on the average, the FE limits of respective Mercedes-Benz specs.
Finally, the mixed system containing the Calcium calixarene OB detergent was positively tested in terms of oxidation, deposits, wear, sludge, as well as emerging issues like low speed pre-ignition and air entrainment. All the tests were run accordingly with ACEA C5/C2/C3, MB 229.71/61/52 and API SN+ specifications.


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