And the Japanese arent resting yet – not even after SAE Internationals adoption earlier this year of definitions for two lower viscosity grades, SAE 0W-12 and 0W-8, developed by Honda. Speaking at the ICIS Pan American Base Oils & Lubricants Conference, JX Nippon Oil & Energy Senior Manager Hiroya Miyamoto said formulators in Japan are now evaluating a super-low-viscosity 0W-4 oil.

We think it is necessary for lubricant manufacturers to continue to develop fuel economy technologies for combustion engines, Miyamoto said on Dec. 4.

The trend toward lighter-viscosity motor oils stems from the push to improve fuel economy and reduce emissions of greenhouse gases. Much of the world now regulates fuel economy and/or emissions, but Japans mandates are among the most stringent. Automakers have numerous ways of improving fuel economy, including cutting vehicle weight, reducing aerodynamic drag, improving drivetrain efficiency and reducing friction losses. But lowering the viscosity of the engine oil is especially popular with them for a simple reason, Miyamoto said: It incurs little expense for automakers.

Japanese OEMs acknowledge that to lower the viscosity of engine oil is one of the most cost-effective ways to lower fuel consumption, he said.

At the same time, automakers recognize that reducing oil viscosity also brings risks – mainly the potential for increased wear and higher levels of oil consumption. Therefore the industry has pushed lubricant suppliers to develop formulations that will contribute to fuel economy improvements without compromising engine protection. Miyamoto said JX Nippon Oils commitment can be seen in its purchase of sophisticated engine test stands and chassis dynamometers which allow vehicles to simulate prescribed driving conditions in a laboratory. Only a few lube manufacturers in the world have this equipment, Miyamoto said proudly.

Using those machines, the company was able to demonstrate that an SAE 0W-16 oil improves fuel economy up to 0.3 percent when the engine is hot and 2 percent when the engine is cold, compared to a 0W-20 product meeting API SN/ILSAC GF-5.

In 2013, SAE International added a definition for SAE 16 oils to J300, the Engine Oil Viscosity Grade Classification System, paving the way for passenger car motor oil standards to include 0W-16 products. Japanese automakers were promoting the use of 0W-16 oils even before SAEs action. Honda was the first, launching its own 0W-16 for factory fill in cars including the Insight, the CR-Z and the Fit 2 in 2009. Nissan and Mitsubishi introduced 0W-16 genuine oils in 2013, and Toyota did likewise the following year. Honda also introduced a 0W-8 genuine oil in 2012.

Except for Toyota, none of the companies displayed the viscosity grades of these oils on their packages, presumably because SAE 16 was not yet a part of J300.

Miyamoto said SAE 0W-16 oils are now a key element of the next North American PCMO specifications, which are currently being developed and due to be adopted in 2018. For the first time, the International Lubricant Standardization and Approval Committee will split its passenger car oil standard into two specifications, ILSAC GF-6A and GF-6B. The sole difference between them is that GF-6B will require a greater fuel economy contribution that can only be achieved with oils that are 0W-16 or lighter.

Miyamoto expects SAE 0W-16 oils will be widely commercially available when the new specifications take effect.

Meanwhile, Japanese automakers are continuing to push the market into lighter territory. Miyamoto said super low 0W-4 oils are now being studied in Japan, and he suggested they could be introduced to the market as soon as 2018.

Japanese OEMs keep challenging [the engine oil industry] to lower viscosity, he said. We still have a gap between the fuel economy challenge and the technology of low-viscosity PCMO.