Hey folks, Today i did a complete flush and refill of the coolant and changed oil filter and Engine oil to Motul 5100 15w50 (1.2L) for the first time in my ns 200. I have clocked 20k km. Coming back to the point, after returning home, i noticed my bike is making a scratching sound from the engine if it is revved above 6 or 7k rpm in neutral gear. ASC guys were super quick to dismiss it. Is new coolant the culprit? There doesn't seem to be a problem in the performance, nothing changed at all other than the increased smoothness. Its just the sound that makes me loose all the confidence while riding. Also, i am not sure if i can hear the same noise while riding on the road as bike is fairly loud post 6k rpm.