Climate change demands urgent actions towards CO2 emission reduction. Through their effect on friction losses, new engine lubricants play a key role in reducing fuel consumption and, consequently, CO2 emissions. Besides oil viscosity optimization, friction contributions are primarily dependent on friction reducer (FR) chemistry, although secondary impacts exist for detergent, dispersant, and antiwear additives.
The authors have been working for several years in the development of innovative friction reducer additives as well as in the definition of testing methods for evaluating the performances of a large number of molecules and selecting the most promising ones for engine or vehicle tests. According to this approach, a tribological method was firstly set up by using the Mini Traction Machine (MTM); this equipment is able to measure friction coefficient under various operating conditions and can also reproduce the Stribeck curve, which embraces all the lubrication regimes, thus qualitatively predicting friction behavior of a lubricant. The performances of a large quantity of candidate additives were evaluated.
Among these, a very promising metal-free additive, derived from renewable sources, was selected and then put in low viscosity engine oils for engine and vehicle test evaluation; standard engine tests, like Sequence VIE and JASO M366 Fuel Economy, as well as chassis-dyno tests were carried out, obtaining results that meet ILSAC GF6a and JASO GLV-1 limits.
The same additive was also evaluated as fuel-borne FR in chassis-dyno tests based on an in-house procedure with CO2 and fuel consumption evaluation. The additive in 95 RON gasoline was compared with the same fuel without additives.
The promising behavior of friction reducer additives at the different scales is the subject of this paper aimed to give a valid support in the roadmap towards CO2 reduction.