The biggest concerns in maintaining diesel engine health are wear and contamination. An engine oil’s four worst enemies are dirt, soot, fuel dilution and glycol, or engine coolant.
Abrasive wear results from a cutting or etching motion caused by circulating hard particles or hard-surface projections wearing away softer surfaces. Abrasive wear sources typically include contaminants, such as dirt, that have entered a component’s oil system and the resulting wear metal particles. Dirt is identified by Spectrochemical Analysis in the form of silicon and aluminum.
Fuel Soot is an indication of an engine’s combustion efficiency. An excessive concentration of soot promotes oil gelling and sludge in the engine, which leads to poor oil circulation. Fuel injector efficiency and timing, the integrity of ring piston seal, oil consumption and load all have an effect on fuel soot concentrations. Results are reported in weight %.
Fuel dilution is the amount of unburned fuel present in an engine lubricant. Most commonly associated with clogged or malfunctioning fuel injectors or fuel system assemblies, excessive fuel dilution reduces lubricity, lowers lubricant load-carrying capacities and increases the probability of a crankcase fire and/or explosion. Fuel dilution is most accurately measured by gas chromatography and is reported in % volume.
A positive result indicates the presence of glycol contamination, most commonly associated with a leak between the crankcase and the engine’s cooling system. Glycol contamination promotes wear, corrosion, lubricant breakdown and sludging. When oil analysis indicates water ingression or the presence of coolant additives, additional chemical tests are recommended to confirm the glycol contamination.