Based on customer feedback and its own research findings, diesel engine maker Cummins is now allowing customers to use the older API CI-4 grade motor oil in most of its 2007 engines.

“Some fleet customers wanted the flexibility to continue using higher ash oils as they gradually transitioned to the 2007 lower emission engine product,” Cyndi Nigh, Cummins' on-highway communications manager, told FleetOwner. “Offering a choice of oil allows customers the flexibility to stock one oil while maintaining the same preventive maintenance intervals.”

According to Cummins, if fleets use CI-4 instead of new CJ-4 oil in their ’07 engines, they won’t need to change their oil drain intervals, but they will mostly likely shrink the maintenance cycle for the diesel particulate filter (DPF). Nigh added that the warranty coverage for its engines isn’t affected by using either CI-4 or CJ-4.

Oil change intervals for Cummins ISB and ISC engines remain at 15,000 miles for both CI-4 and CJ-4 oils, while the ISM and ISX will see oil drain intervals increase to 30,000 miles using CI-4 compared to the 25,000-mile interval set for CJ-4.

“There are two reasons for that,” said Nigh. “First, CI-4 oils contain higher levels of acid-neutralizing additives, [while] the ultra low sulfur diesel (ULSD) now used produces less combustion acids. The combination of the two factors allows for oil life extension.”

The only specific application for which CI-4 oils are not recommended is the ’07 model 7.5 Cummins diesel turbo engine used in the Dodge Ram. “That requires CJ-4 oil,” Nigh said.

However, DPF maintenance intervals will shrink if fleets use CI-4 in their ’07 engines, she noted. “Due to the higher ash content in CI-4 oils, the particulate filter ash-cleaning interval will decrease by 50,000 miles,” explained Nigh. For the ISB, ISC, ISM, and ISX engines, that means the DPF interval drops to 150,000 to 350,000 miles from the 200,000 to 400,000 miles range expected with CJ-4.