Years ago, about 1.5 I bought a C-class with 52tsd km. The car was driven only so little and probably short-haul. About 6 months after the purchase went to the check engine light and the car was alarmingly restless in the state. It was really extreme and the engine was then to go out always on the verge while driving but everything almost normal. Of course, brought the car to the garage. After 3 days, I was finally able to pick him up again. I was told that the injection valve and the ignition coil of 1st cylinder was renewed. Fortunately, the damage was covered by the warranty. I then read through various forums and have become aware during the M271 engine on the problems with coked valves. Since I cant every 2nd-3rd Tankful as a precaution, the valve Clean Liqui Moly one. Whether it is now really brings something, I naturally do not know. However, I prefer to invest the nearly 5 all 1000 - 2000 km, to risk as a cylinder head damage by clamping valves. Of course it's sad that you have to worry about something like that in a Mercedes thoughts. With the engine oil of this company I am very satisfied by the way and have therefore also confidence in this product.
Supplement 11/2013 Meanwhile milage 75tsd KM. During a storage of about 2.5 hours Stop + Go walking pace, which went to MKL. Almost get Hab panic, the car ran flawlessly but with no problems. Ironically, I have purely tilted the last time no valve Clean. Whether there is a connection, of course, I do not know exactly, but I have to read out error memory (P0172 / mixture too rich bank 1) and deleted. Bought at the hardware store, the big box Injection cleaner from Liqui Moly, filled and fully fueled and driven directly 100km highway. So far, all is well, hopefully it remains there.
