i called the mb dealership and they told me that probably the cause of my engine knocking in cold mornings is the thickness of my oil. i'm running 15w40 (i live in south dakota currently, where it get's cold in the winter), and they said the oil is too thick for the lifters when it's cold. also they added that the noise would get worse, and that if i didn't change to a thinner oil (10w30 was suggestedi could cause damage to the engine. what they said doesn't seem that accurate. any suggestions?
also a few days ago i added the techron fuel injector cleaner to the tank. in case i add another one after this gas tank is finished, would that cause any damage to the plastic part of the injectors? i plan on changing the oil right after that. thank you.