Free Advice for Diesel Owners. A major percentage of all problems with diesel engines are related to fuel quality.
Diesel fuel can sometimes vary from one shipment to another or from one area to another.
Customers also switch from one fuel vendor to another and suppliers sometimes change the fuel they are offering. The three things that vary the most in diesel fuel are cetane, weight and viscosity. Cetane is defined as the susceptibility of the fuel to self ignite. Acceptable cetane levels are between 40 and 45, however, very few fuel distributors advertise this since each batch may be different. Cetane can influence both starting and combustion roughness of an engine.