The useful life of engine oil is known to be highly dependent on formulation and the engine operating mode. Consequently, an oil-change interval based on miles traveled or engine operating hours does not necessarily define the in-service quality of the oil. One problem in particular for diesel engines is that oil dispersancy can fail very rapidly. This enables the suspended soot particles to gel the oil even when the actual suspended soot particles are only present at a 1 percent to 2 percent (w/v) concentration. The result of gelling is increased viscosity, poor cold-start protection, more soot abrasion wear, and loss of lubricity. Dispersancy of an oil can be lost when all other oil properties, e.g., oxidative resistance, are still 90 percent intact. Some engine operating schedules_notably high-load to lowload excursions_can lead to total dispersancy loss in less than 100 hours of operation. The research is directed at using scattering of infrared radiation as a means of detecting the transition from well-dispersed particles to the agglomerates that form as dispersancy fails. The wavelength source is chosen to match the effective scattering diameter of the particles and agglomerates in such a way that the transition can be detected as a deviation from classical Rayleigh scattering behavior.The potential commercial application as described by the awardee: Research is providing a much-needed laboratory instrument for oil research using infrared optical components currently available in a number of consumer products. The low-cost of the hardware makes the potential for an enginemounted diagnostic sensor a real possibility.
