Oxidation: Tough Challenge for Heavy-duty Oils


With commercial vehicle demand booming, especially in developing nations, the Asia-Pacific region needs better quality heavy-duty engine oils that can handle extreme conditions and fight oxidation, said Afton Chemical.

Emerging markets account for the majority of commercial vehicle demand today. Based on 2008 data, about 50 percent of all trucks operating were in undeveloped countries. According to Philippe Yannic, Afton Chemicals Braknell, U.K.-based heavy-duty marketing manager, by 2017, this number is expected to be more than 66 percent. In a presentation at the ICIS Middle Eastern Base Oils & Lubricants Conference in Dubai last October, Yannic said that this surge in demand in emerging markets is being fueled by increased demand for commercial and consumer goods that are typically delivered by truck. In addition, many underdeveloped countries have embarked on significant projects to improve transportation infrastructures to aid the movement of goods.

Daimler and Volvo represent 35 percent of the market in these countries, either through direct vehicle sales or joint ventures, Yannic said. And along with this demand for more trucks comes a need for better quality heavy-duty engine oils. Engine oil quality is improving everywhere, mainly due to the fact that sales of new vehicles are increasing, propelling the market toward higher quality oils, he added. The demand forecast for diesel engine oils shows that the fastest growth is expected in mainline engine oils, driven by new vehicle sales in emerging markets and upgrades in quality standards. As a result, Yannic said, formulators of heavy-duty engine oils need to adapt their formulations to the operating conditions in these markets.

Sales statistics show that the average age of vehicles in emerging markets is approaching that in mature regions. In addition, several countries are adopting, or plan to introduce, minimum quality standards, including Brazil, Saudi Arabia, Nigeria, Kenya and Tanzania.

The Main Issue – Oxidation

The main issue for heavy-duty engine oils in emerging markets is that vehicles have to cope with harsh conditions on a regular basis, said Yannic. Common conditions include extreme climates, poor fuel quality, bad roads, overloading and contamination. Also, the wider use of trucks with smaller engines and increased city traffic bring additional challenges. As a result, noted Yannic, engine oil is particularly susceptible to oxidation under these driving conditions.

Africa and the Middle East have significantly more severe fuel quality and climate variations than anywhere else in the world. In addition, road conditions are generally poor. Yannic explained that despite recent high investments in infrastructure, most emerging regions still have a high percentage of unpaved roads. This is a significant issue in the Middle East and Africa, where the number of paved roads in many countries is limited.

In addition, smaller trucks with smaller engines dominate in emerging markets. This trend will continue as rapid urbanization and changes in consumption will increase the need for smaller vehicles, adapted to city deliveries, said Yannic.

OEMs and fleet owners are concerned about vehicle robustness in emerging markets. In fact, Yannic added, vehicle quality and robustness rank among the most important issues for fleet owners, and engine oil plays a crucial role in mitigating damage to vehicles. And oil oxidation is the number one issue in these harsh operating conditions.

Yannic described tests Afton ran to simulate the effect of harsh conditions on diesel engines typical of those used in emerging markets. The test vehicle was a heavy-duty Dodge Ram truck with a 5.9-liter Cummins engine, running the Worldwide Harmonized light-vehicle Test procedure driving cycle.

We measured oil temperature in the engine of the vehicle when empty, weighing 2.7 tons, and when fully loaded, weighing 6.4 tons, he explained. Our testing showed that engine oil temperature increased by up to 10 degrees C due to the load. While this sounds relatively insignificant, it is actually quite a severe impact because the rates of reaction such as oxidation are known to double with 10 degrees C increase in temperature. Hence, it represents a big shift in severity for the engine oil.

Assessing oil oxidation control is paramount to OEMs, Yannic said. And several industry engine tests include a measure of oxidation control, including Mack T-12, OM 646 LA (with and without biodiesel),

Sequence IIIF/G, Volvo T13 and Sequence IIIH, which is under development for PC-11.

In addition, OEMs and industry bodies have developed bench tests to further assess oil oxidation control, he added. A few of them are used for heavy-duty categories such as the Daimler test and the CEC L-109 oxidation test, which is under development for the next ACEA update.

It is still to be decided which categories will incorporate the CEC L-109 test, but most ACEA A/B, C and E categories should be impacted. It will replace the GFC oxidation stability test in the next ACEA update. The test procedure has been established and round-robin tests were targeted for completion by the end of 2014.

The length for the CEC test has been set at 168 hours for heavy-duty oils and 216 hours for light-duty oils.

At 168 hours the CEC L-109 test could represent an increase in severity vs. the Daimler oxidation test.

Impact on Base Oil

According to Yannic, the choice of base oil has a significant impact on performance in oxidation tests. This has been observed in both the Daimler (biofuel and non-biofuel) and the CEC oxidation tests. Based on current Daimler test limits, the use of API Group I alone, using standard additive technologies, is no longer sufficient to meet mainline heavy-duty engine oil specifications, Yannic said. Group II and III base oils, on the other hand, can provide a performance boost to resist oxidation and can help improve field performance under harsh conditions.

Afton studies show that up to 60 percent Group III is required in a formulation along with Group I to meet mainline diesel engine oil oxidation requirements. In addition, we have found that new additive technology can broaden the use of Group I in these applications, allowing Group I base oil manufacturers to maximize their assets, Yannic said.

The ultimate impacts on the base oil landscape for mainline heavy-duty engine oils are threefold, he noted.

First, changes are likely to be driven by the penetration of specific OEMs in a particular emerging market and the need to secure their approvals. Second, the availability of Group II vs. Group III base oils in a particular region will influence base stock selection. Third, additive technology will change significantly depending on the base oil blend. Additive technology can provide formulation flexibility and allow oils to meet the requirements of specification upgrades, Yannic concluded.

Commercial Vehicle Sales 2008-2017




Change (%)

North America




Latin America




Western Europe




Africa & Middle East




Eastern Europe








Source: Automotive World

Heavy-duty Engine Oil Global Segmentation


Typical Performance

OEM Approvals

Drain Interval

Base Oil Type

Vehicle Age


API CF-4 & below



Typically Group I

Limited Group II




API CG-4 to CI-4



Typically Group I

Some Group II

Limited Group III





API CI-4+ to CJ-4



Typically Group II

Some Group II

In Warranty


Factory Fill

Top Tier

ACEA E4 & E6



Typically Group III

Some Group II

Some PAO

Source: Afton Chemical

Lube Report Asia occasionally includes articles originally published in sister publications of LNG Publishing Co. This article was originally published in January 2015 issue of LubesnGreases Europe – Middle East – Africa Issue 67 – under the headline Fighting Oxidation in Heavy-Duty Engines.

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