High viscosity index(HVI) petroleum base stock, with excellent temperature-viscosity characteristics, oxidation resistance, and low-evaporation properties, offers advantages as the base stock for high fuel economy engine oils, particularly because of its low-friction properties in the boundary and/or “E.H.L (Elastohydrodynamic Lubrication)” area due to its rheological characteristics.
This research evaluated HVI base stock's low-friction properties. Upgrading the oil from 5W-30 to 5W-20 was also investigated.
The friction properties of the HVI base stock were measured by a unit friction platform. The results show a 28% reduction in friction coefficient compared with the conventional, solvent refined oil, which is attributable to the high-pressure viscosity of the base oil.
The prototype 5W-20 engine oil, (made with this base stock) with a view to meeting the ILSAC GF-2 standard now expected to be mandatory in the future has been shown to superior to the 5W-30 engine oil in saving fuel consumption, by about 1.8%.