GM Releases Dexos1 Gen 3 Details

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A General Motors official unveiled details last week of the looming upgrade to the companys passenger car motor oil specification. After previously saying it would release Dexos1 Gen 3 in January and begin commercial licensing during the second quarter, the company is considering revising the schedule to push back at least some of the timing and plans to announce a decision soon.

Speaking at the ICIS Pan American Base Oils & Lubricants Conference in Jersey City, New Jersey, GM Power Train Vehicle Fluids Technical Specialist Khaled Zreik said GM made significant changes to align with ILSAC GF-6, the North American auto industrys specification scheduled for commercial launch in May. Gen 3 includes most GF-6 engine tests but also has additional requirements that could complicate work for oil marketers wanting to offer products that meet both specs.

Dexos is the most important original equipment manufacturer passenger car engine oil specification in North America, and Dexos1 Gen 3 is GMs update to Dexos 1 Gen 2, which was launched in 2017. In October GM said it aimed to unveil the new spec in January, begin licensing during the second quarter and require all products promoted as meeting its spec to transition to Gen3 by Aug. 31 of next year.

Lubricant formulators had raised concerns about whether the industrys testing infrastructure would allow lube marketers to obtain approvals within that timeframe. Zreik said GM heard them and is now making a revised schedule that will be announced soon.

The timing for GMs new spec also concerns industry players for a second reason. Many lube marketers offer engine oils that meet both GMs standard and the latest ILSAC spec. With GF-6 scheduled for commercial launch on May 1, many GF-6 and Gen 2 programs are already complete or near completion. Some additive companies and oil marketers have worried that changes to the Dexos standard could impact products already in the pipeline.

Zreik said that General Motors is not satisfied with the industrys ability to keep up with technical challenges that fluids may need to address with new hardware. He confirmed that SAE 0W-20 will be GMs viscosity grade of choice for the foreseeable future for internal combustion engines, which will coexist with battery electric vehicles. Internal combustion engines are trending smaller, while maintaining the same performance as larger previous generation engines. Fluids remain an integral part of GMs drive to improve fuel economy and lower emissions to meet government standards and corporate goals.

Zreik said Dexos1, Gen 3 includes all the new GF-6 engine tests with the exception of Sequence IIIH. The latter is replaced by the GM oxidation and deposit test. GMs test will be stricter, allowing viscosity to increase no more than 75 percent during the test.

The Sequence VH sludge test will also have significantly higher limits than ILSAC GF-6. Although the low speed pre-ignition sequence IX test is included, it is only rate and report for the GM specification. In addition to the GF-6 tests and its own oxidation and deposit test, GM will carry over many Gen 2 methods, including a test for turbocharger deposits at tighter limits.

GM tightened limits on the Gen 3 LSPI test compared to the limits for Gen 2. Gen3 also includes a new fuel efficiency test using a Chevrolet Silverado and a new bench wear test. Definition and requirements for the fuel economy test and wear test are still being finalized. Finally, the specification has eliminated most European tests with the exception of the M271 sludge test, which will also carry over.

In addition to engine tests, changes are being made to some key bench tests and rules for running programs, Zreik said. Notably, the Noack volatility limit will be changed from 13 percent to an average of 12.5 percent on three test runs. The sulfated ash limit will change from less than or equal to 1 percent to 0.9 percent.

Each of these can have a significant impacts on the formulation, changing the base stock mix – especially for the SAE 0W-20 – and potentially causing additive companies to modify the detergent inhibitor package to meet the sulfated ash requirement. GM noted that its specification reduces sulfated ash to protect the catalyst and lower particulate emissions. GM will retain or tighten base oil interchange, viscosity grade read-across or other rules and expects to grant fewer exceptions than it did for Gen 2 approvals.

Zreik said GM has also started to work with customers to update Dexos1 licenses and will add Gen 3 by addendum. Expected changes will include volume reporting requirements and potentially higher fees, although no public information is available on licensing and royalty fees. GM found that 48 percent of marketer labels contained errors that need to be corrected. Marketers who violate requirements can lose their license.