When you check the level in your crankcase, you’ll find the level higher if using CJ-4. That means money saved on make-up oil.

The 2007 emissions standard will bring big changes for truckers. Change can be scary, but the research that makes engines cleaner always does more than just clean the exhaust. It also improves the technology.

These changes bring a lot of good news, especially for those running pre-2007 vehicles. The biggest part of that good news is CJ-4 diesel engine oil, which is so much better than the CI-4 it replaces that it will be well worth the higher cost. CJ-4 is a lot better in the ways it performs in almost all areas, and it needs to pass much tougher tests to prove what it can do.

To decide whether or not you should switch from CI-4 to CJ-4, you need to understand that the fuel, the engine and the oil work together as a system. Once you see how they cooperate, the decision should be easy.

What oil fights
The biggest challenges for oil are heat and the soot, acids and sludge or deposits that form when fuel burns imperfectly. Although the particulate level drops in 2007 to 1/10th what was allowed before, this is not much of a challenge for the engine. A Diesel Particulate Filter or “DPF” (see July Big Rig Basics) will be collecting the soot outside the engine with very little effect on the operation of the engine itself.

The larger challenge for the oil is the 40 percent reduction in NOx or nitrogen-oxides, which is also required. NOx forms when the burning gases in the cylinder get too hot. Most truck makers have been recirculating some of the exhaust since 2002 to reduce the NOx. Exhaust soaks up a lot of heat, reduces the temperature in the cylinder and lowers the NOx.