Assessment of the effect of low viscosity oils usage on a light duty diesel engine fuel consumption in stationary and transient conditions

•The use of low viscosity oils (LVO) lead to lower engine fuel consumption.•SAE 5W20 lubricant diminished the friction losses in the engine.•At low engine speed and loads the improvement effect of low viscosity lubricants is more noticeable.•The “cold start” enhances the low viscosity lubricants effect on fuel consumption.

Regarding the global warming due to CO2 emissions, the crude oil depletion and its corresponding rising prices, OEMs are exploring different solutions to increase the internal combustion engine efficiency, among which, the use of Low Viscosity Oils (LVO) represents one attractive cost-effective way to accomplish this goal. Reported in terms of fuel consumption, the effect of LVO is round 2%, depending on the test conditions, especially if the test has taken place in laboratory or “on road” conditions. This study presents the fuel consumption benefits of a commercial 5W20, compared against higher SAE grade oils, on a light duty diesel engine, when it is running under motored test, stationary fired test and the New European Driving Cycle (NEDC).