While EGR is great for reducing exhaust emissions, one of its downsides is that it can increase the amount of oxidation and acid in the engine’s lubrication system. According to the Society of Automotive Engineers International, there are three main problems that tax a lubrication system that uses EGR: soot; increased levels of acids in the engine; and higher temperatures, which bring increased oxidation of the lubricant. Each problem requires a special additive: for the soot, dispersants and anti-wear additives; for the oxidation, antioxidants; and for the acids, over-based detergent additives to minimise internal wear.Promisingly, researchers from the industrial component major Honeywell and the US chemical company Afton Corporation have come up with a concept for an engine oil filter that automatically meters out additives to the engine oil to combat these bad effects. SAE said that developing a predictable and reliable release mechanism for the additives was key to the project. It did this by adjusting the diameter of the metering tube inside the filter so that the additives were released in a linear way, rather than a one-off high dose.It said testing began with laboratory dynamometer trials using Mack T-11 and T-12 engines attached to dynamometers, and then moved to field validation using eight Volvo D-12 engines and commercially available CI-4 and CJ-4 oils, designed for the 2007 emissions regulations.The testing produced promising results, including a possible reduction in piston deposits when the additives are used.
