In Reply to: Transmission Whirring posted by Doug ///M5 on June 03, 2002 at 15:24:23:
Yes, a low fluid level will cause hard shifting and increased noise. Oil will quiet sounds, and low oil will allow more noise.
To check the throwout bearing, simply start the engine and run in neutral. Push in the clutch. Does the noise get worse? Yes = throwout bearing. Does the noise slow to a stop? Yes = internal transmission bearings.
The final drive is not part of the transmission. They are relatively bulletproof unless you run them without gear oil.
Use regular petroleum ATF if your M5 transmission grinds or is hard to shift, and MT-90 in a newer M5 transmission with fewer miles. Use Red Line 75W90 gear oil in the differential. You will need a 10mm allen socket, a 22mm box-end wrench, and a 17mm box-end wrench to change the diff and trans oils.