Noise after gear oil change

[quoxwood7]

I changed the gear oil on my Sting R MX4 last weekend and now there’s a faint whining noise at mid-speed. I used 75W-90 synthetic. Did I mess something up or is this normal after a fresh fill? thanks

 

[Alan]

If you hear whining after an oil change, it might indicate there's air in the system or that the fluid level is low. The right oil to use is 75W-90. Take a ride for about 20 to 30 minutes and then check the fluid level again. The noise should start to diminish over time.

 

[dirt.e.joe.56]

I changed the gear oil on my Sting R MX4 last weekend and now there’s a faint whining noise at mid-speed. I used 75W-90 synthetic. Did I mess something up or is this normal after a fresh fill? thanks

It's unlikely you messed something up, but since you have a new noise, I agree with @Alan that the first thing to check is the fluid level. But if you find out that the level is perfect, the 75W−90 synthetic is likely the cause since the viscosity difference increases gear mesh noise. That can cause that faint whine at mid-speed. I think as long as your level is correct and the whine isn't super loud or paired with vibration, it's typically just a harmless noise characteristic of that heavier fluid.