I consider myself to have exceptional hearing, always have. I can always "hear" my engines when they make a different or out of normal noise, especially if I've had the vehicle awhile, I get really "in tune" with it. I most certainly can hear the difference between a loud oil and a quiet oil. This is what made my stop using M1 oils years ago. Every vehicle I put M1 in got considerably louder right away. I don't care if it is anecdotal, loudness related to oil type used is definitely a thing.