Fuel Operating Temperature and Viscosity

Since diesel fuel provides cooling of the injection system, the temperature of the fuel may vary considerably due to engine operating temperature. As fuel temperature increases, fuel viscosity decreases along with the lubrication capabilities of the fuel. Maintaining proper fuel temperatures and selecting fuels with the viscosity ranges listed in table “Fuel Specifications,” will ensure the injection system functions properly.

When operating with reduced fuel viscosity or elevated fuel temperatures, the injectors will operate at reduced internal clearances. As a result, dirt and smaller particulate material may cause injector durability concerns. Change filters on Detroit™ On-Highway engines to those specified for “Severe Duty Service.” Installing a fuel cooler or operating with fuel tanks above half full may also help eliminate the concern.