Truck and Track Autumn 2023

Truck and Track Autumn 2023 42 OILS & LUBRICANTS In the world of road transport, the path to reduced emissions is a challenging one, but new technologies and the latest innovations continue to deliver significant improvements. However, there are many pieces to this ‘emissions’ jigsaw and each must be in place for the true benefits to be realised. Since the 1990s, continued legislation has driven vehicle emissions down and down, but to achieve this, engine and exhaust system modifications have had to be made. A variety of emission reduction technologies have been introduced to control the levels of NOx gases and particulate matter (harmful solid debris in the exhaust gas stream). The use and continued effectiveness of these systems have always depended strongly on the quality and performance of the engine oils used. NOx gases can be controlled using Exhaust Gas Recirculation (EGR) and Selective Catalytic Reduction (SCR) systems (AdBlue). EGR creates a severe engine environment, with spent exhaust gases being directed back into the intake manifold. This reduces the amount of free oxygen available to convert free nitrogen in the air to NOx compounds. However, the side effect is incomplete combustion, which creates a large amount of abrasive soot. Soot is not only abrasive, but also affects the flow properties of the engine oil. Without the correct level of oil performance, the engine will experience accelerated wear and oil thickening, which could lead to catastrophic failure. Correctly formulated engine oils control wear and thickening due to soot and will allow the engine to run at optimum efficiency, helping to reduce emissions. The SCR (AdBlue) systems rely on the effectiveness of a catalyst fitted to the exhaust system. AdBlue, a solution of urea, is sprayed into the exhaust gas stream and is carried into the catalyst, where a chemical reaction takes place to remove NOx gases by creating nitrogen and water vapour. However, when the engine oil lubricates the compression rings, valve stems and valve guides, a small amount of oil is burnt, releasing sulphur and phosphorous from certain compounds. As the engine runs, these elements find their way into the catalyst and poison the active sites where the reaction takes place, making the catalyst unusable. Engine oils must be formulated correctly to ensure the additive chemistry provides suitable levels of wear protection without affecting the catalyst. A poorly functioning catalyst will not only be unable to control emission levels, but engine management systems may put the vehicle into reduced power mode (or limp mode) until the situation has been remedied. Emissions and the critical role of engine lubricants Adrian Hill, Technology Manager at Morris Lubricants