I would also agree that there are definite cases of oil consumption, not trying to deny that.
But there are also problems with the oil level monitoring system, and there are also techs who don't seem to "catch on" about how to properly analyze the oil consumption of the engine. I have also seen techs bring the vehicle into the shop, and immediately pull the dipstick and say "yup, it's low!". Nonono, WAIT before pulling the stick, and also hook up the computer and check the monitoring system. They (MB) just really made an easy system very complex, and it's easy to goof up.
I would also agree that if it actually is burning 1 qt every 1000 miles it's pretty unacceptable, although MB in their infinite wisdom does state in the owners manual that 1qt every 600 (!) miles is "acceptable".
But the previous post (mcreynol) I believe has a good point and I have been told as much from MB: If you put in excess oil (even unintentionally) it seems to burn that excess oil off. How exactly it does that without fouling plugs I don't know, wasn't explained.
The dealer in cases like this should perform the oil consumption test, which starts with an oil change, and the car/truck is brought back after about 1000 miles and the shop computer is hooked up and some calculations are done using information stored by the FSS system in the instrument cluster. This will VERY accurately tell the technician how much oil has been consumed, and is a REQUIRED test before MB will allow engine work to be done to correct high oil consumption.


Gilly