Engine Oil Contamination – The Cause of Engine Failure.
If you own, operate or manage a fleet of trucks, it makes sense — operationally and financially — to have samples of used diesel engine oil analyzed regularly. Analysis can tell you how well engines are operating and their general service condition. It will also yield diagnostics to help you spot problems before they lead to engine failure.
It is of utmost importance to keep engine oil free of dirt or particulates. Foreign particles prevent the oil from coating and clinging to wear surfaces. Also, particulates in engine oil become abrasive agents that accelerate premature wear on components.
Water is your engine oil's worst enemy. At the molecular level, water attacks the additives in oil that keep engines running smoothly, and interferes with the oil's ability to properly coat component surfaces. Moisture combines with acids in the oil and becomes corrosive, thus hastening engine wear. Also, the water in oil can react or combine with soot, spent additives, or particulates to create globules that foul oil filters and reduce oil flow to valves, pistons and bearings. Even though low levels of moisture are common in engine oils, higher levels are symptomatic of a serious problem — one that might not be solved by a simple oil change.
Glycol may enter engine oil as the result of failures in the engine's cooling system due to faulty or blown seals and gaskets, cracked cylinders, or corroded engine components. Studies have shown traces of glycol in 8-16% of long-haul rigs, with excessive glycol present in 1-2% of them. Like moisture, glycol reacts with oil additives to compromise the oil's ability to lubricate. It also increases the oil's viscosity, preventing the free-flow of lubricant to engine components. The presence of glycol contamination is 10 times worse than the presence of moisture when it comes to engine wear.
Under certain conditions such as excessive idling, cold running and frequent starts and stops, fuel may find its way into the engine oil and cause problems. Severe (> 2%) fuel dilution may be caused by poor combustion efficiency, faulty fuel injectors or other leakage. Fuel dilution can drastically alter oil's viscosity (and hence its flow) and can accelerate wear on piston rings, liners, and crankcase bearings.
Soot is a by-product of combustion that's present in all diesel engine oils. Excessive levels of soot, however, indicate poor combustion performance and need to be corrected. Soot can accumulate and form deposits on and around engine surfaces, eventually compromising engine performance and reliability. High soot and sludge levels may indicate poor ignition timing, a spent air filter or excessive ring clearance. These possibilities should be checked out and, at the very least, an oil change is called for.