General Motors is putting the finishing touches on the next generation of its proprietary Dexos engine oil specifications, expected to be ready in 2015 for 2016 model year vehicles – a full two years ahead of the industry-wide GF-6 specification.
Eric R. Johnson, industry liaison for fuels and lubricants with GM Powertrain in Milford, Mich., unveiled the new generation specs at the ICIS Pan-American Base Oils & Lubricants Conference in Jersey City, N.J., last week. Johnson introduced new specs for both Dexos1, for spark-ignited engines, and Dexos2, for diesel engines.
GM first introduced Dexos2 for factory fill in Europe for 2010 model year vehicles, and Dexos1 for North American factory fill for 2011 model year vehicles. Today, more than 200 engine oil brands are Dexos-licensed, including all the major brands in North America, Johnson noted.
Goals of the Dexos program are first to have a global common engine oil specification for factory and service fill, said Johnson. Other key goals include fuel economy improvements, engine oil robustness improvements, more catalyst-friendly fluids, and hardware-enabling engine oils that control aeration.
With engine life monitors now in more than 90 percent of GM vehicles, GM requires oils that compliment the oil life monitoring system and give customers lower cost of ownership and improved satisfaction through optimized drain intervals.
The original Dexos1 featured 11 engine tests, a combination of CEC, ASTM and GM engine tests, plus chemical and physical tests, while the original Dexos2, also a combination of CEC, ASTM and GM tests, called for 15 engine tests. The original Dexos 1 spec is more robust than ILSAC GF-4 and GF-5, said Johnson, and Dexos2 is more robust than ACEA C3 and API CJ-4.
Objectives for the next generation Dexos are fuel economy, turbocharger deposits, aeration, stochastic pre-ignition, wear, oxidation and deposits. Twelve engine tests are slated for Dexos1 approval: CECs M-271 sludge test and M-111 fuel economy test; ASTM/ILSACs Sequence VH, VID/VIE and VIII; and seven proprietary GM tests.
Johnson reported in depth on the status of five of the engine tests. The Sequence VIE fuel economy test, he said, has shown exhaust valve leakage at some labs due to deposit build-up. The build-up can be eliminated using a top-tier fuel additive, which is now being used in the test. Test duration has increased from 155 hours to 200 hours.
More than 20 GM oxidation and deposit tests have been completed, and GM is ready to finalize test cycle conditions. The test procedure and test stand set-up kit will be available in the first quarter of 2014, and the precision matrix will begin then.
Likewise, 20 GM aeration tests have been completed on 20 oils provided by several additive companies; nine oils are ready to evaluate for viscosity grade and antifoam effects. The precision matrix is expected to start in the first quarter of 2014, and the next steps include evaluating Dexos1 and Dexos2 performance and establishing aeration targets.
Twenty-four GM turbocharger deposit tests are completed, and the test procedure is expected to be available in early 2014, with precision matrix expected to start in the first quarter.
Finally, Johnson reported that GMs stochastic pre-ignition test using a 2.0 liter direct-injected turbo is currently evaluating additive technologies and calculating test precision. GM expects to finalize test procedures in early 2014 and identify reference oils in the first quarter.
The next generation Dexos must help GM comply with the U.S. Environmental Protection Agencys 2016 fleet limit of 35.5 miles per gallon and 2025 limit of 54.5 mpg; and with Europes 2015 CO2limit of 130 grams per kilometer and 2022 limit of 95 gm/km.
In addition to providing increased fuel economy and reduced emissions, Johnson continued, the new Dexos must be compatible with global use of oil monitors.
The Dexos licensing program continues to be handled by the Center for Quality Assurance in Midland, Mich. The Dexos web site,www.GMdexos.com, will soon be split into two sites, Johnson concluded, to provide more licensing assistance to additive and oil companies seeking licensing information and support.
