I'm not sure of the benefit of continued discussion focusing on what a 6 or 7 year old FSM/Owner's Manual recommends with respect to oil specifications in today's oil market. With that in mind I'll redo and suppliment, below, my post at
viewtopic.php?f=5&t=72256&p=759224&hilit=MS+10725.#p759224The 05/06 DCJ FSM says "API categories CF or better and the requirements of DaimlerChrysler Material Standard MS-10725" and the Owner's Manual specifically speaks to SAE 0W-40 Mobil 1.
1. I cannot find and I don't know that anyone has ever found a copy of the MS-10725 or, if it's been found, 1) a translation to API or 2) a list of oils available TODAY that meet the standard. For what it's worth 0W-40 Mobil 1 does not appear to meet MS-10725 or at least it's not listed as meeting it on the Mobil 1 site (
http://www.mobiloil.com/USA-English/Mot ... W-40.aspx#) although it is listed as meeting the long outdated CF standard, see below.
2. API ratings change over time and CF is a 1994 standard that's been out-of-date since 1998 when it appears to have been superseded by CH-4 (see
http://www.api.org/certifications/engin ... 120210.pdf). I have no clue why that dated standard was listed in 05/06 manuals other than the obvious copy/paste problem. In fact IMHO what those manuals should have listed when published was CI-4. Based on today's API ratings CH-4 to CJ-4 oils are ok so long as you are using fuel with sulphur content below 500ppm. In the context of today please note that CI-4 is for engines running "higher" sulpher fuel than currently used in the US.
3. As to oil "weight" see
http://www.blackstone-labs.com/oil-viscosity.php for a discussion of what multi-weight oil ratings actually mean. The take home message is that the North American and export market CRD Owner's Manuals contain different oil weight/viscosity recommendations although as I understand it the primary difference is the "lower" number (e.g. they all recommend XXW-40). I imagine the difference has to do with DCJ's guesstimate as to ambient operating temperature range in the particular market which I find a bit of a hoot as the continental US climate can range from 120F in Tempe, AZ to -40F or worse in northern states (I've excluded Alaska).
IMHO, while the oil weight/viscosity certainly matters it matters more that you keep the oil soot content down by some combination of GDE tune and relatively frequent oil change intervals. I know some have done it but I, personally, think oil change intervals upwards of 8-12k miles are just asking for trouble and I won't go past 6,000 miles. Sorry but in the real universe oil is cheap and turbos/rockers/blocks are expensive. The same pretty much goes for using synthetic vs staight dino given the tiny oil passages in our engines. NOTE geordi and others have noted that some of the CRD oil passages are really really small so exceeding XXW-40 is probably a very bad idea and because of oil passage size I'm not at all sure there is any merit in comparing our oil requirements to those of a TDI as a lot of the discussions do.
So my

use a name brand good quality appropriate API (CH/CI/CJ-4) diesel rated synthetic oil with a change interval of ca. 6,000 miles and a weight consistent with the climate at your specific location. 0W-40 is probably fine for the colder climates, 5W-40 would be a good middle ground, and 10-15W-40 to the extent it's available would be ok for really hot areas. Use the block heater if at all possible for cold starts when the ambient temp is below say 20F (certainly below 10F) and when the weather is cold avoid long idling (it won't warm the engine up much and certainly won't warm up other drive line fluids) but also avoid higher speeds (above say 35mph) until the temp gauge shows some signs of life.