Good evening, can someone please explain the difference between transmission oil 75W and transmission oil 75W-80 to me. In my car the clutch was changed, if I let go of the clutch in the stand you can now hear such a light flap noise. If you then kick the clutch and let go again it is usually gone. It is also not always there. It comes from the rear end of the transmission. Drive and switch it can be quite normal. Filled in Mannol MTF -4 75W-80, instead of the prescribed a Tutela Transmission Gearforce 75w.Do you think the sounds can be caused by the wrong oil?