At this point I think condition, mileage, and service records are of greater significance than which engine is chosen. I currently own one of each - a 1993 300E 2.8 and a 2001 E320 wagon. In normal driving they are almost indistiguishable - perfectly smooth, responsive, and quiet. Add a bit of throttle and they both get aggressive, pulling hard at upper RPMs with a sporting growl. Different notes, of course, an I6 doesn't sound like a V6.

In terms of repairs, the M104 has required both a head gasket and engine wiring harness prior to 100K miles. As I understand it, the engine wiring harness is not a concern in a 96/97 model year car.

The M112 hasn't needed any repairs. Of course, it's only 7 years/55K miles old.

The professional techs on the site do report occasionally reringing the M112/M113 V6/V8 engines. So far I haven't seen any data points that correlate, or not, this failure with use of conventional oils. I don't know whether this failure occurs to the unlucky or only those that don't follow proper maintenance procedures. I can recall 2 occurances of folks on this site that needed new rings.

The 722.6 five speed automatic is a nicer driving transmission than the earlier four speed. It has a better selection of gear ranges, and is more cooperative in choosing the correct gear. It delivers better fuel mileage because it has an overdrive top gear and a lockup torque converter. But unless you can afford a late 99 or 2000 model year, when all the updates were incorporated, I wouldn't recommend it over the earlier transmission.

My long and rambling $.02,

- JimY

Jim - great post and I agree with all of it. While I haven't seen any directly correlating data on your point above, the successful lawsuit against Mercedes in the USA by O'Keefe was based on this exact premise. That 1998-2000 MY Mercedes exhibiting oil consumption issues, and that followed FSS intervals yet used mineral oil, were to be repaired under warranty by Mercedes. The issue of course was that Mercedes failed to specify the TYPE of oil to be used in North American cars. The European standards were higher (still are) and hence the cars were already using synthetic overseas. Here in North America, the dealers used regular oil or blends and then ran the engines to the full FSS interval.

It doesn't take much engineering or biochemical knowledge to know that an oil designed to run a maximum of around 5,000 miles shouldn't be run to 10,000 miles or over. Hence the damage, and hence the oil consumption.

My car had intervals of over 17,000 Km on conventional oil. This up to about 80,000 Km or so. I don't think it is a coincidence that my engine is now consuming oil. Whether from sludge or permature wear due to the oil not being able to lubricate properly is something I may never know. No help from MB Canada either, no lawsuit up here and my car is now over the 10-year mark.

__________________
Chris
2007 E550 4Matic - 61,000 Km - Iridium Silver, black leather, Sport package, Premium 2 package
2007 GL450 4Matic - 62,000 Km - Obsidian Black Metallic, black leather, all options
1998 E430 - sold
1989 300E - 333,000 Km - sold
1977 280E - sold
1971 250 - retired

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