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general motors dexos1™ gen 3

new passenger car motor oil specification

Dexos1™ Gen 3 is a global engine oil specification introduced by General Motors (GM). The new specification is designed to meet performance needs of GM vehicles and is an upgrade from dexos1 Gen 2. Newer versions of GM's fuel economy and stochastic pre-ignition (SPI) tests, along with upgraded deposit and sludge test performance limits, dictate a higher level of performance over the previous generation’s specification. Oronite is prepared to meet the latest GM specification, leveraging the knowledge we gained from the launch of products and solutions for ILSAC GF-6 in 2019. We use testing methodology that includes both laboratory and real-world test environments. Before GM’s specification release, Oronite was already evaluating its technology in field tests to demonstrate capabilities in key performance areas of the dexos1™ Gen 3 specification.

Dexos1 Gen 3 will be used by GM to meet their new hardware performance needs. GM has once again improved performance with dexos1 Gen 3 in almost all areas, adding increased performance limits for the existing tests and replaced the legacy GMVFE and GMSPI tests with more demanding versions. More rigorous testing ensures even greater engine protection than today’s challenging industry standards. There is some overlap with dexos1 Gen 2 when compared to the latest industry standard, ILSAC GF-6, but dexos1 Gen 3 still has enhanced aeration, turbocharger protection and engine cleanliness.

Chart depicting dexos1 specification differences
Variances in the generations of dexos1 specifications.

frequently asked questions

What is the current timing for dexos1 Gen 3 products licensing?

Originally, GM announced the first license date for dexos1 Gen 3 as May 1, 2021 with dexos1 Gen 2 claims expected to be obsolete after May 1, 2022. However, in April 2020, the GM dexos1™ team announced a delay in the release of the specification due to the uncertainty of the COVID-19 pandemic. In early August 2020, GM announced the start of dexos1 Gen 3 testing as September 1, 2020; first license date September 1, 2021; and that dexos1 Gen 2 claims are expected to be obsolete after September 1, 2022.

What is meant by “cascadability”?

Oronite’s new dexos1 Gen 3 products will have different treat rates based on your requirements. Fully cascadable additive technology can simplify your logistics and help reduce costs. One flexible additive means only one tank to supply all your products. Within the bottom and top of the cascade, there are many options for performance differentiation.

What is the difference between GM’s new Stochastic Pre-Ignition (SPI) test and Low Speed Pre-Ignition (LSPI) tests used in GF-6?

Stochastic Pre-Ignition (SPI) is also known as Low Speed Pre-Ignition (LSPI). It is an abnormal combustion event where the fuel-air mixture ignites before intended, similar to “knocking.” The main difference from knocking is pressure. SPI or LSPI events can result in pressure spikes up to 130 times atmospheric pressure, which is about 2.5 times the normal pressure in the engine. This can cause a catastrophic mechanical failure, but it can be controlled by your motor oil. Many OEMs are developing in-house LSPI tests for their own engine designs. GM's dexos1 specification now includes a GM stochastic pre-ignition test (GMSPI). This test is similar to the Ford LSPI test used in GF-6, albeit at different operating conditions.

New and upcoming engine oil specifications include low speed pre-ignition (LSPI) prevention. ILSAC GF-6 includes a Ford engine test to discriminate oils based on LSPI event prevention (reduction). Thus, all oils that make ILSAC GF-6 claims are formulated to address LSPI. The new GMSPI test will incorporate transient engine testing (aggressive throttle and engine speed changes) and is expected to be more severe over the previous generation test.

Chart depicting Stochastic pre-ignition
SPI, or LSPI, phenomena have the potential to break engine parts and can cause audible noise.

Engine oil formulations have an impact on the frequency of LSPI events based on initial work performed by Oronite and several other industry experts. Various studies have taken place to investigate the impacts of fuel, lubricant, hardware, and other factors, on LSPI. Certain lubricant components have been found to promote LSPI while others are neutral or can actually suppress LSPI. For example, Calcium, Iron, Sodium metals have shown to promote LSPI while Molybdenum and zinc dialkyldithiophosphates (ZnDTP) tend to suppress LSPI.

Many of these compounds are included in the engine oil formulations to provide performance in various areas. They can’t simply be removed without affecting other areas of performance. In order to formulate for LSPI, a rebalance of compounds is needed to provide needed performance in all areas, not just LSPI performance.

Will the upgraded dexos1 be backward compatible with the previous generation dexos1?

Dexos1 Gen 3 will be backward compatible with previous generation dexos1. GM has outlined a timeline for final “sale” of dexos1 Gen 2 targeted to be Sept 1, 2022 (one year after first license for dexos1 Gen 3).

Is there a diverging technology pathway between GF-6 and the dexos1 Gen 3 specification?

We do not expect diverging technology pathways here. Dexos1 Gen 3 includes a number of the ILSAC GF-6 required sequence tests and is viewed by GM as more of a “tightening” of the Gen 2 specification rather than a “step change.”

Are Group II+ base oils allowed in dexos1 Gen 3 formulations?

Group II and II+ base oils are certainly allowed in dexos1 Gen 3 formulations, but GM will allow limited to no read-across for formulations that contain greater than 30 percent Group II/II+. This typically applies to 5W formulations and could possibly apply to 0W formulations with a Group III+ or PAO trim fluid.

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