China Drafts Heavy-duty Gas Engine Oil Spec

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China Drafts Heavy-duty Gas Engine Oil Spec
Orange gas cylinders for a truck that runs on liquefied gas. © FOTOGRIN

A draft standard for lubricants for heavy-duty engines running on natural gas has cleared the project review stage and been formally accepted as a development project of the China Society of Automotive Engineering.

The society will now seek input on the draft and then conduct test trials to gauge whether it discriminates between oils that provide the desired performance and those that do not.

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The society said the project is a priority because China’s government considers gas-powered trucks an important cog in its strategy to reduce automotive emissions of greenhouse gases and because numbers of such vehicles are increasing in the country.

“In order to improve the selection and testing of heavy-duty gas engine oils by Chinese automobile manufacturers and end markets, it is urgent to develop a standard for heavy-duty gas engine oils to fill the gap where there is no industry standard for products in this field,” the society said in a posting about the standard on its website.

Gas-powered vehicles represent a small fraction of China’s overall heavy-duty truck population, the society said – limited mostly to provinces such as Inner Mongolia, Shanxi and Xinjiang that produce large amounts of gas. Within those areas, though approximately 20% of trucks run on gas. The society said natural gas is a relatively clean fuel, and it expects the numbers of trucks running on it to grow rapidly in coming years.

“In the long term, natural gas will become the most promising ‘low-pollution fuel’ for vehicles, and in the short term, its important position as an alternative fuel will not be challenged,” the organization said.

As is the case for stationary gas-powered engines, the lubrication needs of automotive engines running on gas differ in some ways from engines running on gasoline or diesel. The society said that because natural gas combusts completely, metal ashes in the engine oil are critical to controlling wear of intake and exhaust valves. Ash content that is too high, however, will cause premature ignition and cause valves to melt. In addition, the relatively high combustion temperature of gas tends to increase generation of nitrogen oxides, accelerating oxidation and deterioration of the oil.

“In summary,” the society said, “gas engine oils must have suitable sulfated ash content and excellent oxidation resistance, nitrate resistance and anti-wear properties.”

PetroChina led the writing of the draft standard, which was initiated by FAW Car, Dongfeng Motor, Yuchai Power, JAC Motors, Sinopec and Yuchai-Petronas.