GREENSBORO, N.C. – Assuming things go according to schedule, the new PC-11 diesel engine oils should be ready for purchase beginning in April 2016.
For that to happen, the final product specifications need to be delivered by the American Petroleum Institute’s (API) New Category Evaluation Team (NCET) by the end of Q2 2015, explained Dan Arcy, global OEM technical manager and industry trade association liaison for Shell Global Solutions.
During a technical briefing for trucking and transportation journalists, Arcy outlined some of the thresholds and benchmarks, the new, yet-to-be named (the PC stands for “proposed changes”) oil will have to meet. All engine oil currently on the market needs to pass a number of tests before it can be approved for use by engine manufacturers, and the PC-11 oils will be no different. Seven of the existing CJ-4 tests will be carried over to the new standard and used as part of the evaluation process. But PC-11 oils will also have to pass three new tests and one modified test.
The first of the three new tests is an aeration test performed on a Caterpillar C-13. The second is an oxidation test run on a Mack T-13, which Arcy called “a very severe test, more severe than we’ve ever had in the category.”
The third is a shear stability test with more stringent requirements than have existed in the past. Shear stability is measured by what is known as a Kurt Orban 90 pass test. The current pass is set at 9.8 centistokes (cSt). The proposed standard will likely be around 12.8cSt for all xW-40s except 0W-40 which will remain at 12.5cSt. (xW-30s will stay in grade.)
The modified test is expected to be a scuffing/adhesive wear test performed on a Detroit Diesel DD13. The engine will be run for an extended period of time (125 or 150 hours, the final standards haven’t been set yet). The power level will gradually be stepped up to a maximum of 510hp. There will be a four-hour hot soak every 25 hours, and the engine will be equipped with non-coated, but otherwise production-standard piston rings. The test will evaluate how long it will take for scuffs to appear on the liner how much top ring weight loss occurs.
The seven carryover tests are:
• soot/viscosity in EGR engines (Mack T-11)
• ring and liner wear (Mack T-12)
• soot/EGR valvetrain wear, valve stem/guide wear (abrasive and corrosive) (Cummins ISM)
• soot valvetrain wear (Sliding Wear) (Cummins ISB)
• piston deposits, Fe and oil consumption (Caterpillar C-13)
• piston deposits, Al and oil consumption (Caterpillar 1N)
• soot valvetrain wear (abrasive and rolling) (RFWT)
“Oils will get thinner because engines are getting hotter, and because we’re running thinner oils to start with,” said Arcy. “Customer don’t want to give up engine life to get better fuel economy.”
According to Arcy, there is likely to be a split standard for the new category. PC-11A higher high temperature high shear (HTHS) xW-30 oils are expected to be fully backwards compatible with existing engines. They will be evaluated when operating at 150C as opposed to the 100C operating temperature used to test CJ-4 oils. In comparison to current CJ-4 oils, which have a viscosity of 3.5 centipoises (cP), the PC-11A oils will be rated at 4.2 cP.
Lower temperature HTHS oils will fall under the PC-11B category. These lower viscosity lubricants won’t likely be backwards compatible and will only be used in 2016 or 2017 and newer model year trucks. They are expected to rate between 2.9 and 3.2 cP and provide the best fuel economy while maintaining engine durability.
While NCET is still working on finalizing the tests and developing the benchmarks, Shell has been conducting field trials of its own experimental oils—oils designed to meet the PC-11.
“We’ve been taking CJ-4 additives, blending them down into PC-11 levels and putting them into field trials,” said Matthew Urbanak, lead formulator for Shell Rotella heavy duty engine oils.
At present, Shell has over 200 vehicles participating in the test, with over 25 million accumulated miles. The vehicles belong to fleets operating across North American, in a variety of conditions.
“Our testing indicates low viscosity oils can maintain engine durability, even at 10% extended ODI (oil drain intervals) above 500,000 miles,” said Urbanak.
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