Whistling Noise from a Honda Civic

My 1999 Honda Civic (automatic transmission), makes a strange whistling noise when I accelerate past 60. I have had mechanics look at it and I’ve been told everything is ok with the car. However, I had another mechanic look at it recently and he said that at some point someone might have put a transmission fluid that’s different from what Honda recommends and it might have caused the whistling noise. Has anyone encountered this problem before?



The car has about 96,000 miles.