Fuel System 55 Cetane Number Direct injected diesel engines require a minimum cetane number of 40 under normal starting conditions. Fuel with a higher cetane value may be required for high altitude or cold weather operation. Filtration Fuel should be clean and free of contamination. Clean fuels should have no more than 0.1% of sediment and water. If fuel is stored on site, make sure that: Keep storage tank covered to prevent water entry. DO NOT use a tank made of galvanized metal or any galvanized piping for diesel oil storage. Diesel will react with the zinc, forming solids that can clog fuel filters and cause engine damage.
Fuel stored for a long time may oxidize and form solids, causing filtering problems. Keep the area around the fill cap clean. Tilt the tank slightly toward the drainplug area so water and sediment can be easily drained. Generally, fuel contamination occurs as the result of improper fuel handling. The most common types of contamination are water, dirt and microbial growth (“black slime”). The formation of varnishes and gums resulting from poor fuel stability or long storage (“stale fuel”) also affects fuel quality. The best treatment for contamination is prevention by maintaining a clean storage system and choosing a reputable fuel supplier.