For those old, tired diesel engines with hundreds of thousands of miles, if you are having abnormal oil consumption (more than 1 gallon per 10,000 miles/1 month) and you are currently using a 15W-40 viscosity diesel oil, try bumping up your viscosity to a 20W-50. Over the years, the clearance between the rings and cylinder liner has been growing, resulting in more and more oil consumption. Try closing up the gap with a thicker oil, which will provide great engine protection as well as help reduce consumption.
Information provided by: Amsoil
