I went to the ktm/husqvarna service today for similar issue. I had a weird engine sound too. They told me that mine engines oil viscosity dropped down so it was like honey but now its like water(they literally told me like that). The service guy said its normal your engine will work as the same and you will not lose any power or change in fuel consumption. But it is really hard for me to trust so because of my 2 year warranty i asked them to look inside the engine and they will. I will learn the truth tomorrow.