I have worried about the use of synthetic oil (Mobil One) during the break-in period of my Benz. It is not encouraged or recommended by several of the synthetic oil manufactures or other auto manufactures. I questioned my dealer and they assured me that Mercedes knew what they were doing. Nonetheless I researched the issue and found the most compelling information on the subject of engine break-in procedure and necessity to be in the aircraft engine industry. From the information I compiled it seems reasonable to conclude that if using synthetic oil, the break-in period would need to be longer in duration and more strictly adhered to. Since I could not think of any down side to a prolonged break-in period except that it would prevent long trips and be slightly less exciting. I basically went 4000 mile under a somewhat more stringent than proscribed procedure and then had the oil changed. I actually would have preferred changing the oil every thousand miles but all the information found supported the prolonged use of synthetic oil, though not specifically during the break-in phase.
So far I have not noted any oil usage, and time will be the better judge (only 8K since February). I was actually surprised when I took delivery of my C230K that the salesman recommended a reasonable break-in regiment. I know many people whom have purchased new cars and were not advised to, nor do they believe engine break-in is required. I have seen some of these vehicles billowing blue smoke at 60 to 80 thousand miles. From my experiences, I can tell you that the first 500 to 1000 miles of treatment are very critical to an engines long-term health when using standard oil and maybe even more with synthetics. I have owned since new and driven several vehicles to mileages as high as 350,000 with no major engine repair. As a matter of fact to this day I still drive an 87’ VW with over 350K several times a week, not as much fun as the C230K, but I don’t have to worry as much either.
The problem of oil usage may not be a random occurrence, but more a function of early treatment. It would be nice to have more data on this issue, so maybe some input from others about how they broke-in their vehicles and if they have had any problem with oil usage would be helpful.