Powertrain and fuel diversification - challenges for engine oils

The article explores the rationale behind the necessary diversification of powertrains and the energy carriers used in the energy transformation of transport. Ongoing research and analyses indicate that it practical for piston internal combustion engines to remain the primary propulsion system used in transport, commercial transport in particular, during the transitional phase leading to complete electrification of transport. The promotion of fuel decarbonization is a critical step in combating climate change. As a result, zero or low carbon fuels such as methane, hydrogen, ethanol, methanol and even ammonia are becoming increasingly significant. These developments in powertrains and fuels direct influence the necessary changes in lubricants used in the automotive industry. Therefore, the lubricant industry must diversify into lubricants designed to meet the requirements of a wide variety of powertrains. This diversification should aim to enhance efficiency, performance and durability, simultaneously reducing harmful emissions and optimizing production costs. This requires overcoming a number of barriers related to the conflicting requirements placed on lubricating oils by, e.g., internal combustion engines. These requirements include contributing to the reduction of primary emissions, safe and reliable operation of exhaust aftertreatment systems, and the interaction with fuels of different compositions. The article specifically details the requirements for engine oils, depending on the powertrains and fuels used. Particular attention was paid to the associated with the compatibility of engine oils with specific fuels. In the case of reciprocating internal combustion engines, the need to address the increasing contribution of burnt engine oils to total particulate emissions was highlighted. The advantages and future prospects for the use of synthetic fuels are discussed in this context. Additionally, the article delves into the lesser-known problems that engine oils must counteract in hybrid drive systems. The implications and specific requirements for engine oils when using currently underutilized but definitely promising fuels such as hydrogen and ammonia are discussed as well. The final section of the article extensively describes the various requirements placed on lubricating oils for electric powertrains. In electric power units, the lubricating oil used in transmissions increasingly commonly serve also the purpose of a cooling fluid for direct-cooling electric motors. The direct contact of lubricating oil with the components of electrical assemblies elevates the importance of its electrical insulating properties. In general, lubricating oils should improve mechanical efficiency and reduce hydraulic losses of a transmission in order to reduce electricity consumption and CO2 emissions of an electric vehicle generated during the generation of electricity. An added challenge in the development of lubricants for electric drive systems is the absence of specified technical requirements for fluids in electric vehicles to date. Additionally, there is a lack of standardization of test methods and definition of the scope of the necessary tests for these fluids.