Idemitsu Develops Ash-free Diesel Engine Oil


Idemitsu Develops Ash-free Diesel Engine Oil
A truck in Japan in Tokyo's Shibuya Ward. © Ned Snowman /

Japanese lubricant blender Idemitsu Kosan developed an ash-free heavy-duty diesel engine oil with no metallic detergents while maintaining anti-wear performance, the company claimed recently.

The product, Idemitsu AshFree, is a phosphorus-free, ash-free engine oil with no metallic detergents or zinc dialkyldithiophosphate. “Based on our findings, it is the first ash-free diesel engine oil in Japan,” a spokesperson told Lube Report.

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Globally, ashless engine oils are more commonly formulated for use in engines powered by natural gas and in diesel railroad locomotive engines. Examples of applications include stationary industrial engines powered by synthetic or natural gas, naturally aspirated and turbocharged 2-cycle natural gas engines and light-duty 4 cycle engines.

“Idemitsu AshFree has cleanliness and wear resistance equal to or greater than Jaso DH-2, and we have confirmed that there is no problem with durability for Japanese truck diesel engines,” she added.

The company said in its press release that its additive formulation technology has a sulfate ash content and base value within DH-2 limits and has been tested and passed all engine tests in the performance standard. DH-2 is a Japanese diesel engine oil standard for buses and trucks equipped with exhaust gas after-treatment equipment such as diesel particulate filters.

Conventional diesel engine oils used in truck and bus engines contain metallic additives to improve cleanliness and wear resistance. 

However, a major challenge for blenders is that anti-wear metallic components such as ZDTP in additives turn into ash, clog the DPF and negatively affect the performance of the catalytic converter, while phosphorus is absorbed on the surface of the exhaust catalyst, reducing performance.

Idemitsu said it verified the oil’s ability to prevent piston deposits on a hot tube test and that the oil then passed wear tests run on Caterpillar and Hino engines.

Idemitsu AshFree is sold in Japan in a viscosity grade of 10W-30 in 200-liter drums and 20-liter cans since Sept. 1. 

“In the future, we will consider expanding overseas, mainly in Southeast Asia, when exhaust gas restrictions come into force,” the spokesperson said.