New oil on the block

| November 08, 2006

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.

The 40 percent reduction in NOx will be met with familiar systems – EGR (exhaust gas recirculation) and Caterpillar’s ACERT, with Cat adding a slightly different form of EGR called Clean Gas Induction.

It was having more exhaust from EGR going through most engines that worried engine oil makers and motivated them to develop the CJ-4 grade. What worried them most was additional heat and pressure, especially the heat. When an engine needs to recycle more exhaust, both the heat and pressure in the cylinder are likely to increase. The heat goes up because the exhaust is warm – nearly 300 degrees F. – and there will be more of it. The pressure goes up because there’s more total stuff going in – the same amount of air plus the additional exhaust.

Heat attacks the oil mostly where it sits between the piston and cylinder liner when lubricating those parts. It also reaches the oil where it flows inside the top of the piston, right under the crown, to cool it. Too much heat can have a very destructive effect on engine oil.

An additional worry was soot in the oil. Having a lot of exhaust in the cylinder often results in more soot getting around the piston, onto the cylinder liner and into the oil, though no more soot may come out the exhaust pipe.

Where CJ-4 is better
The oil makers went to work and developed new and better super-oils to combat the additional stresses.

“To meet the enhanced performance requirements of the 2007 engines, the CJ-4 oil is designed for better oxidation stability, high soot dispersion capability, better piston deposit control, increased wear performance and reduced oil consumption,” says Reginald Dias, director, commercial products, ConocoPhillips Lubricants.

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