CO₂ Emissions Reduction by Using Low Viscosity Oils in Public Urban Bus Fleets

CO₂ emissions and fuel consumption reduction in road transportation has become one of the most relevant concerns either for governments, original equipment manufacturers (OEMs) and final users, especially fleet owners and managers, led mainly by global warming and rising fuel prices concerns. For vehicles driven by internal combustion engines (ICE) the fuel consumption rates are directly related to CO₂ emissions, the latter being a consequence and an efficiency indicator. A wide variety of solutions have arisen to overcome this challenge ranging from hybridization to changes in the vehicle-design looking for more aerodynamic profiles, to solutions like eco-driving courses for drivers or the usage of alternative fuels such as biofuels. All of these solutions vary in technical complexity, implementation costs and terms. One proven cost-effective way to reduce the fuel consumption is the use of low viscosity oils (LVO) in order to reduce the engine inner friction, reducing by this way the amount of energy required to move the engine parts resulting this in a fuel consumption reduction. This paper presents a study where the effect of the use of LVO on urban transport buses on the CO2 fleet spot and fuel consumption, based on a comparative test where 39 buses worked for nearly a year separated in two groups each of them carrying either LVO or standard viscosity oils.