Referring to my recent posting about my C180 Euro making crackling noises around 2000rpm as I accelerate, it seems that this is common to the C class with this motor i.e. the 4 cylinder. I put in some Nulon injector cleaner potion last night and went on a quick freeway dash for about 50kms and it now sounds a lot better. The noise??pinging?? or is it due to valves sticking?or bad mufflers? I will try the Octane Boost potion soon and wonder if any owners of these 4 cylinder Benz motors have experienced any change in the speed or running. There is also a petrol conditioner or engine fuel conditioner which I have seen on shelves.