The need for PC-11 was first spelled out in June in a letter from The Engine Manufacturers Association to the DEOAP, which represents both engine builders and the oil industry. The EMA cited four reasons why a new category was needed:

1) Engine technology has changed to meet emissions mandates and fuel economy standards, and there’s greater use of renewable fuels.

2) Hardware designs have changed since the current category, API CJ-4, was commercialized five years ago.

3) By the time the new heavy-duty oils debut, it will have been 10 years between categories. EMA asked that PC-11 oils be launched in the market by January 2016.

4) Many engine tests for CJ-4 are becoming obsolete and their hardware unavailable.

The letter set in motion the procedure outlined in API Document 1509 (Appendix D) for evaluating, developing and introducing new heavy-duty engine oil categories. The initial step was the formation of a New Category Evaluation Team.

That team first met on Aug. 19 in Baltimore, where they reviewed EMA’s request for a new category and began deliberating whether to recommend to the Diesel Engine Oil Advisory Panel, and in turn to API, that a new category should be developed.

Among the questions the team posed were: What is the proposed change and why is it required? Does data presented support the request? When is it needed in the marketplace? What are the potential impacts on engines, consumers and the environment, and on existing API categories?

The evaluation team also asked if performance tests are available to properly evaluate PC-11 oils, and if the perceived benefits outweigh the projected costs. The issue of paying for the category’s development also arose: How much will it cost to develop test procedures and determine their precision? What is the estimated total cost to carry out projected work for the new category, if the need is approved?

The team met again on Sept. 15 in Chicago, and reviewed data that supported EMA’s desire for improvements over API CJ-4 in areas such as oxidation stability, aeration and shear stability. EMA also identified a need for better biodiesel compatibility and scuffing/adhesive wear.

Two new engine sequence tests — a piston/liner scuffing wear test and a shear stability test — will be needed for PC-11, as well as revisions to three other tests. Tests for thermal stability and oil aeration need to be upgraded, the team heard, and new hardware for existing tests will have to be integrated into the proposed category. The oil upgrade also should include testing with biofuels to measure their impact on corrosion, deposits, oxidation and low-temperature pumpability.

A new twist is the inclusion of a lower viscosity oil for fuel economy. Viscometrics alone are being used to define the oil’s contribution to fuel economy, based on data which show lower high temperature/high shear viscosity gives better fuel economy. PC-11 will have two targeted HTHS limits: the current 3.5 mPa.sec minimum for traditional engines, and a lower HTHS limit (currently thought to be no lower than 2.9 mPa.sec) for fuel economy.

How much will it cost to develop PC-11? That question will be addressed by yet another task force, one that will estimate the costs of running precision tests as well as base oil interchange and viscosity grade read-across test matrices for every new or revised test in the category.

That task force includes representatives of OEMs, oil marketers, additive companies and engine test labs.

User language will be needed as well for the new category. The API Lubricants Group will research how to label and market the two different HTHS grades, to avoid confusing consumers.