It is expected that the world's energy demand will double by
2050, which requires energy-efficient technologies to be readily
available. With the increasing number of vehicles on our roads the
demand for energy is increasing rapidly, and with this there is an
associated increase in CO₂ emissions. Through the careful use of
optimized lubricants it is possible to significantly reduce vehicle
fuel consumption and hence CO₂.
This paper evaluates the effects on fuel economy of high
quality, low viscosity heavy-duty diesel engine type lubricants
against mainstream type products for all elements of the vehicle
driveline. Testing was performed on Shell's driveline test
facility for the evaluation of fuel consumption effects due to
engine, gearbox and axle oils and the variation with engine
operating conditions.
To complement the rig-based testing, a field test protocol has
been developed to better understand the linkage between operating
conditions and fuel economy changes when driveline lubricants are
changed. Two standard, delivery-type, 18-ton trucks have been
modified with fuel-flow, engine operation and GPS (global
positioning system) measurement equipment. Following a fixed
on-road test route in the UK containing city, local, highway and
hill driving conditions, the fuel consumption data was separated
out for each situation to demonstrate the relative differences. To
minimize variability, tight controls were placed on the test
set-up, measurements taken and the operation of the vehicles.
Using a Mercedes Benz OM 460LA heavy-duty diesel engine run
under the World Harmonized Transient Cycle (WHTC) and World
Harmonized Stationary Cycle (WHSC), a combination of a SAE 5W-30
engine oil, SAE 75W-80 gearbox oil and SAE 75W-90 axle oil gave
average fuel consumption improvements of 1.8% and 1.1%,
respectively, relative to a SAE 15W-40 engine oil, SAE 80W gearbox
and a SAE 90 axle oil. Using the WHSC cycle, significant variations
in the individual lubricant contribution under different speed/load
conditions within the cycle were identified. Additionally, an
average fuel consumption improvement of 1.8% was observed using
medium-duty trucks under a range of typical European driving
conditions in a controlled field trial.
