A method for monitoring the condition of oil in an engine is disclosed which includes the steps of determining a plurality of parameters, determining a fuel injection model, determining the area of the cylinder walls that is coated with fuel, and responsively determining a total base number (TBN) model....http://www.google.de/patents/US5987976?utm_source=gb-gplus-sharePatent US5987976 - Method for determining the condition of engine oil based on TBN modeling
