If you are using oil at the rate you report, you have engine problems.

Best information I have is that there were more than 15,000 W140 cars with OM603.97 engines made/sold worldwide and many/most seemed came to the US or went to Japan. There were about 3000 W126 cars with the 603.97 engine by my count. That's approaching 20,000 engines - there were some used in G-wagons too, but I have NO numbers for them. Mercedes has acknowledged that the engine failures were confined largely to US cars (but they have NOT ever actually acknowledged that there is an engine problem with the OM603.97 engine). I have communicated with about 100 owners of cars with these engines. More than half of them have had replacement engines installed. Most were replaced before the engines reached 100kmi and more than 90% of the replacements occuring before 150kmi. I know of owners with 200-300+kmi on the original engine and NO evidence of any malfuntion. I know of two replacement engines (I've included yours) that seem to have failed the same way that the original engines did. I know of one that was destroyed by serious abuse - and I just won't count that. This is a very much lower failure rate than the original engines exhibited (this is NOT a sample that can be considered as being representative, but seems pretty representiative of the MB owners that I know). By 5 years of age the original engines were failing at a high rate. After more than 5 years, the rate of failure of the replacement engines is MUCH lower.

The highest percentage of failed engines that I've seen were in cars that were used largely (50+%) or almost exclusively for city driving. Cars that are used almost exclusively for highway driving seem to have a far far lower failure rate. The reports of failures of original engines has dropped dramatically in the last few years despite almost half the original engines still being in service and most of them having well over 100kmi on them with some having 200-300+kmi. I hadn't gotten a report of one in more than 6 months until I heard of yours. A few years ago I was getting more than a report a month. Oil consumption on these "good" engines (as well as replacment engines) is just about what other OM60x engines display - maybe a qt every 5-7kmi.

More than half of the original OM603.97 engines THAT I KNOW OF that are still running today, use Mobil synthetic oil (either Mobil 1 or Mobil Delvac 1) with a few more using Amsoil synthetic (base stock supplied by Mobil but a different additive package). I do not have any proof that the oil makes any difference, but I have a BIG preference for it based on my own measures of engine wear, improved cold weather starting and lifter noise. Oil sure can't reverse wear or damage that has already occured or damage caused by trying to compress something that is incompressible, but it can reduce wear dramatically at cold start (much less friction) and timing chain wear rates on all of my OM60x engines dropped by more than 50% when they were switched to Mobil synthetics and even when running (fuel economy improves measurably, but by only a few percent in my experience) when conventional oil is replaced by synthetic).

Marshall