2 years ago, I came across this article but the link doesn't seems to work any more. Luckily, I had cut and paste and save it on my pc. It's interesting reading. FYI, I think the JASO DX-1 is the code name for the new spec. and when it's ready for launch, they rename it JASO DH-1. Hence some confusion.
http://www.lubrizol.com/DieselTrends/dtrends100.htm#JASO
Extract from above www.
JASO DX-1: Performance for Japanese Diesel Engines
JASO DX-1 is the new diesel lubricant specification currently under development for Japanese heavy duty engines. This proposed specification incorporates test procedures from North America, Europe, and Japan.
Outside of Japan, Japanese OEMs have been recommending API CD oils for service fill for many years. However, some field performance deficiencies with API CD have been observed. The Japanese Automobile Manufacturers Association (JAMA) does not believe that any of the current API specifications fully address their performance needs and are, therefore, proposing a new specification for higher quality oils to meet the increasing requirements of their new, low emission engines. The JASO DX-1 specification will address three key performance areas: valve train wear, piston deposits and exhaust gas recirculation (EGR).
A primary concern of Japanese OEMs has been the potential for valve train wear (VTW) with high dispersant oils. Relatively high levels of VTW had been observed in OEM evaluations of API CG-4 oils. Therefore, the Mitsubishi 4D34T test was developed to measure VTW protection in diesel lubricants in a typical Japanese engine.
Another major OEM concern has been piston deposits. Typically, the top ring is positioned lower on the piston in Japanese engines com-pared to the low emission designs in Europe and North America. This generally results in lower top ring temperatures in Japanese engines. Since recent piston deposit tests in the industry were developed to address temperatures hotter than those characteristic of Japanese applications, the Nissan TD-25 test was included to measure piston deposits under conditions typical of Japanese diesel engines.
The third OEM concern has been exhaust gas recirculation (EGR). EGR significantly increases the potential for high levels of acid in the oil and resulting engine component corrosion. JASO DX-1 is therefore likely to include a minimum TBN requirement of 10 by ASTM D4739, which is approximately equal to 11-12 TBN by ASTM D2896.
http://www.lubrizol.com/DieselTrends/Trends9/requirements.htm
Extract from above www.
Diesel Trends 9
Oil Performance Requirements for JASO DH-1
On October 10, 2000, the JASO Engine Oil Implementation Panel officially introduced JASO DH-1, the new diesel lubricant specification for Japanese heavy-duty engines.
The quality of JASO DH-1 diesel lubricants for 4-cycle diesel engines is specified under the Japanese Automobile Standard JASO M 355:2000. This standard specifies the lubricant performance required for engines that meet the strict exhaust emission regulations in Japan, as previously discussed in Diesel Trends 8. It requires oils with improved performance for abrasive-wear and corrosion protection, high-temperature oxidation stability, and soot control. In addition, it specifies performance related to controlling piston detergency, high-temperature deposits, foaming, oil consumption due to volatility, viscosity after shearing, and seal compatibility.
After many years of using API CD oils, the Japanese OEMs have started the Millennium with aggressive schedules to introduce higher-quality diesel engine oils to meet increasingly stringent emission requirements.
Japanese OEMs are expected to adopt JASO DH-1 as the specification for factory-fill oil as well as service-fill oil. OEMs are likely to introduce and promote DH-1 within the Japanese market before extending it to other Asian regions. It is the intention of OEMs to use the Asia Fuels and Lubricants Conference and other trade/industry conferences as forums to promote the use of DH-1.
Although JASO DH-1 was developed for new engines meeting strict exhaust emission regulations, it can also be applied to engines manufactured before the establishment of the regulations. In addition, it can be used for diesel fuel with sulfur content exceeding 0.05%, provided that the oil change practice is in accordance with the OEM's recommended drain intervals.
