Which Oil?

Unlike previous API oil classification changeovers, this time, oil companies decided to keep offering the CI-4-Plus oils along with the new CJ-4 category oils. In the past, the old category oil was taken off the market as the new one went into the system.

This change in strategy was in response to consumer demand, due in part to the fact that the new oils cost 5 percent to 10 percent more, and in part because of uncertainty about what the new oils meant for extended oil drain intervals.

This means you've got some decisions to make regarding which oil to use. Do you use the new oils in your 2007 engines and keep using the old oils in your pre-2007 fleet?

Or do you switch the entire fleet over to the CJ-4 oils, reaping what the oil companies say are performance benefits in older engines, but paying a higher price up front?

Having one product simplifies operations and maintenance; with mixed product, there's always the possibility that the wrong oil will get into the wrong engine.

Comfort Zone

"Although CJ-4 products do offer the benefit of improved soot handling, oxidation and deposit control, some operators may decide to stick to what they are comfortable with for their older equipment," says Steven Goodier, technology manager for BP Castrol.

For instance, a smaller fleet with 50 units and only one truck with a new engine "may be able to keep the CI-4 Plus lubricant and buy CJ-4 in smaller quantities" for the new engine, says Reginald Dias, director of commercial products for ConocoPhillips Lubricants.

How your oil provider supplies the different oils may make a difference in your decision. At the Technology and Maintenance Council meeting earlier this year, some maintenance managers said they were basically being forced to use the CJ-4 oils because their distributors were offering only the new oils in the bulk packaging they needed.

Adding another wrinkle to the equation, Cummins has said while it recommends CJ-4 oils in its 2007 on-highway engines, it will permit the older CI-4 Plus oils to be used. But there is a trade-off in shorter DPF maintenance intervals.

John Shepard, commercial on-highway marketing specialist for Chevron Products Co., explains that "during service, the DPF captures carbonaceous particulate matter, which is known as reversible because it is burned away inside the DPF. Lubricant consumption, on the other hand, leads to an irreversible accumulation of metallic ash in the DPF. Eventually metallic ash can clog the DPF, restricting exhaust flow and engine power," and leading to the need to have the DPF serviced. Ash content of the lube oil, which is higher in the CI-4 Plus oils, can hasten this ash accumulation.

"The tradeoff, if a customer chooses to use the CI-4 Plus oil, is the cleaning interval will be shortened – approximately on the order of 50,000 miles," says Louis Wenzler, director of on-highway market communications for Cummins. "So if the DPF would go out to 400,000 miles on the low-ash (CJ-4) oil, it would be like 350,000" on the older CI-4 Plus oils.

Cummins sees the option as a strategy for some customers to help manage the transition of their fleets to 2007 engines and eventually to CJ-4 oils. It's an option that a number of customers expressed interest in.

"If you think about a trucking operation that has a fair number of vehicles, say 2004, '05, '06 models, they're running the CI-4 Plus oils today," Wenzler explains. "So now they're going to purchase some '07 engines, but 90 percent of the fleet is older units. For some fleets it could be advantageous to remain with one oil in the shop.

"As time goes on, and there are more '07 units coming into the fleet, it probably makes sense at some point in the future to transition to run CJ-4 in everything."

Some other engine makers may also allow customers to do this; if you're interested, discuss it with your engine supplier.

Weighing All The Factors

As you're making the decision on which oil to use, make sure you look beyond the initial cost of the oil. "Let's say the new oil is 50 cents more a gallon," says Mark Betner, heavy-duty lubricant manager for Citgo Lubricants.

"A Class 8 truck probably uses 60 to 80 gallons of oil a year – so what we're talking about is about a $40 investment per year per truck. If I've got 100 vehicles, you've asked me to spend $4,000 over the course of a year on the new oils. Could CJ-4 oils help get that $4,000 back? If you were at X drain interval and you could increase that 20 percent, you would more than get that money back."

Similarly, if you're running Cummins engines and opt to continue using the CI-4 Plus oils in the handful of 2007 engines you're buying, do the cost savings in initial price make up for the more frequent maintenance of the diesel particulate filter?

"There is a slight cost increase for CJ-4 oils, but when you start to really look at the cost of servicing DPFs, it just doesn't make sense," says Dan Arcy, product marketing manager for Shell Lubricants. "The cost of servicing far outweighs the extra cost for the oil."

Look at cost per mile when making your decision, advises BP's Goodier. "Take into consideration not only initial purchase price, but the maintenance costs, not to mention the resale/replacement cost of machinery. CJ-4 has been a major challenge to the industry, but has resulted in a step change improvement in oil performance. A fleet engineer should establish if this will benefit his fleet operation."