Motor Oil for Diesel Engines
CJ-4 vs. CI-4

The ongoing debate over the new oils being released for the 2007 engines is heating up.

The major oil refiners/manufacturers/blenders are in a tough spot. Motor oil has always been backwards compatible, meaning a new oil can be safely and effectively used in older engines.

In the current situation where CJ-4 (PC-10) and CJ-4 Plus oils are now coming online the question about how effectively, safely, and completely then can replace the current CI-4 and CI-4 Plus is becoming a serious concern.

There is good reason to question this new oils use in pre 2007 engines and especially in pre 2002 engines.

First, what is different about CJ-4 and CJ-4 Plus oils.

The CJ-4 and CJ-4 Plus oils are Group II base mineral oils with additive packages that are 25% to 30% of the total package.

The motor oil in the new 2007 engines will operate at much higher temperatures due to the EGR systems. This places the oil under extreme thermal stress and will reduce the oils useful life even with the improvements in thermal stabilization. The use of current CI-4 oil in a 2007 engine will likely cause problems with oil thickening due to the high heat and is not recommended for those engines.

Oxidation will be a bigger problem as the high heat and EGR system will accelerate chemical breakdown of these oils.

There will be very high levels of soot production due to the EGR systems and the way the engine manufacturers are "tuning" the new engines to reduce NOx emissions. This very high level of soot production will quickly contaminate the motor oil in spite the advanced detergent-dispersant packages included in the new oils. Many users will find it necessary to cut their oil change intervals in half.

The EPA has forced the oil producers to limit some of the most important components found in heavy duty diesel oils. There are serious reductions in sulfated ash, zinc, phosphorus, and sulfur. These important components have long been the basis for the highest quality oils. Sulfated ash absorbs and neutralizes acids developed in the combustion process; zinc, phosphorus, and sulfur protect metal components against wear, provide extreme pressure (EP) lubrication, and offer a cushioning effect between components.

The CJ-4 and CJ-4 Plus specifications likely represent the practical upper limits of mineral oil technology for diesel engines

The pre 2007 and especially pre 2002 engines will likely suffer increased component wear and reduced oil change intervals when using the CJ-4 oils. Off-Road engines using high sulfur and low sulfur diesel fuels will not have the ability to neutralize and absorb the high levels of acid produced by burning those fuels. This will at a minimum result in the need to change oil much more often and is likely to cause accelerated component wear and degradation.

When you consider that the new CJ-4 and CJ-4 Plus oils will likely cost 15% to 20% more than the current oils and will likely not perform as well in pre 2007 engines you have to ask yourself if it the right thing to use.

We are recommending that customers carefully review your engine manufacturer's owners manual regarding oil specifications. Engines requiring CJ-4 and or CJ-4 Plus oil should definitely use those oils. However on engines that specify a CI-4, CI-4 Plus, or earlier specification of engine oil, we suggest that you continue to use CI-4 Plus oils as long as you can find it.

Additionally Well Worth offers engine oil flush equipment, high quality engine oil flushes, and motor oil supplement products to protect your investment in equipment and extend its usable service life.