SAN ANTONIO. Lubricant experts from Exxon Mobil and Shell interviewed here at the 10th annual Rush Truck Centers (RTC) Technician Skills Rodeo believe the introduction of the new PC-11 diesel engine oil blends expected by December next year may encourage a “step change” in the use of engine oil changes as a central preventive maintenance (PM) time marker.
That’s because the longer oil drain intervals many fleets seek to attain results in fewer PM opportunities to check other fluids and components, noted Douglas Tucker, key accounts manager for Shell Lubricants.
“We had one customer actually dial back their oil change interval from 45,000 to 24,000 miles for that reason,” he told Fleet Owner. “That’s because longer intervals between oil changes resulted in longer intervals between PMs, meaning they missed inspection opportunities where they could catch potential component failures and safety issue items.”
Randy Edwards with Exxon Mobil agreed with that observation, adding that if fleets continue to desire longer oil drain intervals, they should consider using an alternative marker for PM, such as tire wear/inflation inspections. “This is creating a ‘step change’ in how PMs are scheduled,” he told Fleet Owner. “Historically, it’s been the oil change driving PM schedules. Now it may need to be something else.”
The introduction of the new PC-11 oil category expected in December 2016 may also add another wrinkle to PM practices as two new blends should be introduced, Exxon Mobil noted.
In a presentation provided to technicians competing at RTC’s skills rodeo, the lubricant maker said that PC-11 A – expected to be termed CK-4 – may be backwards compatible only to a degree, either encompassing engines back to the 2013 model year or perhaps as far back as 2010.
However, PC-11 B – expected to be called FA-4 – won’t be backwards compatible, meaning that fleets may end up having to stock two engine oils depending on the mix of equipment ages within their operation.
Just having to stocking two different oils, with one of them not backward compatible with older engines, may create further complications for fleet maintenance strategies, Exxon Mobil said:
- Using two PC-11 blends will require two separate oil storage and dispensing systems, increasing maintenance costs;
- The risk of cross-contaminating engines with the improper oil blend becomes an issue;
- Warranty claim denials may result if cross-contamination occurs;
- Older engine failures may increase if they are filled with the wrong oil blend;
- Yet fuel economy improvements may be lost if newer engines aren’t filled with the FA-4 blend.
Exxon Mobile Edwards stressed that the reason the new FA-4 oil PC-11 spec is being created is due to the greenhouse gas (GHG) emission rules issued by jointly by the National Highway Traffic Safety Administration (NHTSA) and Environmental Protection Agency (EPA) several years ago that in effect mandate improvements to heavy truck fuel economy.
“This is all being driven by the need to increase fuel efficiency,” he explained. “Now, the [new FA-4] oil itself doesn’t increase fuel economy. What happens is that it’s lower viscosity simply reduces how much fuel is needed to push the engine pistons up and down due to lower friction. Less work means less fuel is burned.”
