Engineers use spider graphs like this to compare the characteristics of oil.

Because of low SAPS, most oil suppliers recommend against using CJ-4 in these non-road diesel engines, but it will work if you shorten drain intervals.

Before negotiating your 2007 oil purchase, decide what your requirements should be. Will you be ordering any new trucks in 2007? When will the trucks be put in service? How much non-road gear do you operate? What fuel does it use?

CJ-4 is designed to suspend soot and contamination in finer sizes and greater quantities than CI-4 Plus. It withstands heat better, improves wear protection, controls deposits, improves oil consumption, and has better soot-related viscosity control. It will also cost an estimated (as of fall 2006) 20% more than CI-4 plus.

If you will not add any 2007 vehicles, the price differential alone suggests staying with CI-4 plus. If and when 2007 on-road equipment comes in, you must run it on CF-4 oil.

If faced with an emergency situation when you must add oil to a 2007 vehicle but only have older oil, you can top off without damaging the engine, provided you drain the oil at the earliest possible time, and then refill with the new oil.

CI-4 Plus will not harm the engine in a short period, but it will affect DPF life-to-cleanout, depending on how much oil is added and how long it stays in.

For some, CI-4 Plus will do. Others should change to CJ-4, balancing higher costs with expected benefits of longer engine life. Still others will find it worthwhile to store and use both grades, but take care not to get them mixed up.

Paul Abelson is senior technical editor for RoadKing and Land Line magazines, both serving the trucking industry. He is a former director of technology and maintenance control. You can e-mail him

New Online Mechanics Training

Chevron's Lubricants University,, a Web site focused on lubrication and coolant issues, recently introduced two new self-study courses. Fundamentals of Industrial Gear Lubrication and Fundamentals of Heavy Duty Coolants have been added to its catalog.

The site offers Web-based, self-study courses designed for maintenance professionals interested in ongoing training without having to spend significant time away from their primary duties. All Lubricants University courses offer a certificate of completion once a student has completed the training.