Also known as COAT and ASTM D8047, the oil aeration test is one of two new diesel tests – the other being the Volvo T-13 – that were introduced for the new diesel engine oil categories. CK-4 and FA-4 were launched in the second half of 2016 and were permitted to be displayed in the API donut beginning on Dec. 1, 2016.

There are currently more than 800 licensed CK-4 products and over 90 FA-4 products already approved for 240 marketers from around the world. In addition, additive companies have already completed the vast majority of programs needed to deploy these products, so although there may be some niche new investments or even research into more optimal technologies, marketers can still easily deploy new products based on the existing approval work.

Most of the diesel engine oil sold in North America is CK-4. FA-4 was the newest category available at a lower viscosity level for improved fuel economy. Although many products are available, commercial use of API FA-4 products are limited as not all original equipment manufacturers allow its use at this time, and for those that do, the product has limited or no back serviceability to older engines, limiting its application.

Hind M. Abi-Akar, fluids technical expert from Caterpillar Inc., explained the reason for the COATs unavailability. The Caterpillar Surveillance Panel took action to improve the variation in calibration test results across test labs, she told Lube Report.The surveillance panel agreed to suspend candidate testing while the aeration measurement systems among the labs were made uniform.

Abi-Akarwas the key leader when the COAT test was developed. At this time, the test setups among the labs are uniform, hence this step has been completed, she said. The first phase of validation was successfully completed. The second phase has delivered some unexpected results, which the surveillance panel is evaluating.Once the results are fully understood, the surveillance panel will determine the necessary course of action to bring the test back to a calibrated status.They will also update industry on how long the outage will last, but the test is expected to be back in service this year.

Provisional licensing allows oil marketers to obtain licenses for CK-4 and FA-4 oils without passing the COAT, so long as they pass all other tests. API puts them on its list of licensed oils without any special designation. Once the COAT is again available, provisionally approved oils will have six months to pass it.

As long as a second test for CK-4 and FA-4 does not become unavailable, industry should easily manage this disruption. It should be noted that industry will also need the COAT test to maintain older diesel categories such as CJ-4, CI-4 and CH-4 when the older Engine Oil Aeration test (EOAT or HEUI test) becomes unavailable. Parts for the 1994 vintage Navistar 7.3L test are no longer available, and only one test stand remains, but many tests can still be run on it.