I have a 2013 Ford Mustang with an MT82 6-speed manual transmission. I don't know the history of the car so I figured it would be a good idea to change the transmission fluid. I drained it out and pumped new fluid back in.

I have done many automatic transmission drain and fills but this was my first time owning a manual car. I believe I may have underfilled it a bit. After reading online the car was not completely level and was at a slight incline probably causing the fill hole to falsely let me believe it was full when it was not.

I drove it around for a mile or two and now the car makes a bad noise when in neutral and the shifter shakes. When I put the transmission in neutral and push in the clutch pedal the noise goes away, but as soon as I release the clutch pedal it starts making a bad grinding noise. When I press the accelerator to increase the revs in neutral the noise goes faster.

I jacked the car up and made sure it was level and full, but it still seems to make the same grinding noise. I put a full 3 quarts in until the hole started to leak.

I was looking for some general advice... reading online it seems to suggest that the input shaft bearing may be the problem... not sure if there is anything else I can try.

  • 1
    "When I put the transmission in neutral and push in the clutch pedal the noise goes away, but as soon as I release the clutch pedal it starts making a bad grinding noise" That is a bad input shaft bearing, doubtful anything you did.
    – Moab
    Sep 6, 2020 at 1:22
  • Did it make that noise before you changed the fluid?
    – Solar Mike
    Sep 6, 2020 at 5:37
  • No, I don't recall it making any noise before I put the fluid in. I am really confused what happened, perhaps it was wearing out and that was the straw that broke the camels back? It had 130k miles.
    – Super1337
    Sep 7, 2020 at 17:08

2 Answers 2


Since you stated there is only a slight incline the level of the fluid should only be some millimeters below the fill hole. That should be tolerable. Assuming that you used the right kind of transmission fluid one can assume that you only had some bad luck, especially as the M82, according to a quick googling, has numerous issues.

Short anecdote:

I am feeling with you. I had exactly the same issues (albeit not a American muscle-car, but on a diesel powered bread and butter family car). I decided to preemptively change the fluid on a bad-reputation transmission, followed the latest service bulletins and filled it with the correct amount of the correct fluid. The first bearing made some noise about a month later.

Ok, what to do now?

I'd bring it as soon as possible to the local transmission specialist. The sooner it is repaired the less is to replace.

  • Thanks I think I put the right fluid based on the manufacturer specs... it is Motorcraft XT11-QDC. I am thinking I am going to run it to the shop.
    – Super1337
    Sep 6, 2020 at 20:10
  • Go for a good shop, transmission repair is the black magic of the trade. It needs particular skills and particular equipment.
    – Martin
    Sep 6, 2020 at 20:22

Long ago , when I had manual transmissions, it was difficult to get the heavy oil into the transmission (as a amateur without equipment) . So it was not unusual to drive with the oil level an inch below the fill level . That did not bother clunky old 3 speed transmissions.

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