General Motors (GM) has introduced the second generation of its dexos1™ specification, a proprietary spec that helps ensure GM vehicles around the world are serviced with high-quality motor oil needed to maximize performance and protection.
The new specification is driven by the global market shift toward higher fuel economy. The implications for oil marketers are significant, as second generation dexos1 requires considerably higher-performance lubricants than current API and ILSAC industry standards.
Like many specifications, GM’s required performance will be verified by a range of tests including some required for ILSAC GF-6 as well as several new GM proprietary tests. Each test correlates to a critical area of engine performance as identified by GM, many specific to gasoline direct injection (GDI) and turbocharged GDI (TGDI) engine performance.
Lubrizol recognizes the importance of higher-performance lubricants that protect and enable modern, fuel efficient engines, and strives to keep its customers and partners up to date on the latest developments. Here’s what you need to know about the tests incorporated in second generation dexos1:
GM Stochastic Pre-Ignition (SPI) Test: This test evaluates a lubricant’s ability to prevent low speed or stochastic pre-ignition, a problem specific to common TGDI engines. LSPI can lead to knock resulting in engine damage, and preventing engine from reaching peak fuel economy. Oils must demonstrate the ability to eliminate pre-ignition events under the test conditions.
GM Aeration Test: Lubricants are increasingly used as a hydraulic fluid in modern engines—oils now cool, lubricate and serve important hydraulic functions, including supporting the functionality of bearings, variable valve timing and hydraulic lift devices.
As such, resistance to aeration has become a critical performance measure of the modern lubricant. An aerated oil becomes slightly compressible, compromising its hydraulic functionality. The GM Aeration test evaluates a lubricant’s ability to resist aeration during varying durations of engine operation.
GM Turbocharger Deposit Test: The GM Turbocharger test evaluates a lubricant’s resistance to coking and buildup at extreme temperature operation. Turbochargers are an important means by which many automakers are achieving fuel economy goals. They run at extreme temperatures, thus posing the risk for oil coking, or solid residue buildup from high heat.
This residue can block feeding and drain tubes to the turbocharger, compromising performance. Clear feeding and drain tubes are critical, as turbochargers require a constant stream of reliable lubrication.
GM Oxidation and Deposit (GMOD) Test: This test is under development and aimed at replacing the current Sequence IIIG test used in dexos1. This test is critical because at high temperatures and heavy loads, lubricants can become oxidized, leading to viscosity increases and piston deposits. Viscosity increases or thickening can have negative consequences.
Fuel Economy Tests: As mentioned, fuel economy drives dexos1. The new specification incorporates several tests that directly measure a lubricant’s contribution to fuel economy gains. These include:
- The Sequence VID Test: The industry standard for measuring fuel economy contributions of a lubricant. It will be replaced by the Sequence VIE test when available (same test is included in the proposed GF-6 specification).
- New European Drive Cycle (NEDC) Fuel Economy Test: The NEDC test utilizes a full chassis dynamometer instead of a simple engine stand. This means the test measures fuel economy gains across the entire vehicle, rather than just the engine, and can simulate many different driving conditions.
A full chassis dynamometer introduces many new variables to fuel economy testing, meaning that it becomes inherently more challenging to demonstrate significant fuel economy gains attributable directly to the lubricant.
Additional Tests: The remaining tests ensure that with all the gains that must be made in terms of fuel economy, a lubricant’s durability and contributions to engine cleanliness are not compromised. Many are existing tests, and include:
- GM Valve Train Wear Test: Similar to the Peugeot valve train scuffing/wear test, it further tests an oil's ability to prevent valve train wear.
Peugeot Valve Train Scuffing/Wear Test: Evaluates prevention of valve train scuffing and wear under intense conditions.
- GM Oil Release Test – (OP1): Evaluates oil durability under severe test conditions.
- Peugeot High Temp Deposits, Ring Sticking, Oil Thickening Test: This test has similar criteria to the GMOD and Sequence IIIG test. It evaluates prevention of thickening and deposits at higher temperatures, along with ring sticking.
- Sequence VG Low Temperature Sludge Test: Evaluates a lubricant’s control of engine deposits under operating conditions designed to increase sludge production.
- M271 Sludge Test: Using similar criteria as Sequence VG sludge test, this test further evaluates a lubricant’s control of sludge buildup.
- Sequence VIII Bearing Corrosion Test: Evaluates lubricant protection against bearing weight loss.
New Heights In Performance
The performance standards set by second generation GM dexos1 are unprecedented. As such, it’s expected that many existing product lines will not meet the requirements, necessitating widespread reformulation. Additionally, no existing testing data from first generation GM dexos1 certification will carry over for recertification—all new test data must be submitted.
For these reasons, Lubrizol urges oil marketers to evaluate current product lines in order to identify how and where they may be challenged to reformulate.
To meet the strict demands of second generation GM dexos1, it will require advanced formulation techniques and the right additive chemistry. Through its constant market engagement and unparalleled testing capabilities, Lubrizol has developed the additive chemistry necessary to achieve unmatched fuel economy, and continues to push the boundaries in what is possible through additive chemistry.
To learn more about a partnership with Lubrizol in order to achieve certification under second generation GM dexos1, contact your account representative.