I am going to change my differential oil tomorrow in my 89 GT and I was wondering if anyone had any tips. I have a very loud whine in my rear end when I accelerate. The car has 3.73 gears in it. Just wondering what is the easiest way to drain the fluid? Should I remove the cover or just the bolt and use a pump? I was going to replace the current oil with royal purple 75w145. Thanks in advance for any tips.

 

Since you have a noise, I would pull the cover so you can get a look at the gears, how they are meshing and make sure there aren’t metal shavings/chunks at the bottom of the diff, and so you can clean the magnet at the bottom of the diff housing. Good luck...

 

when did the whine start or, has it always been there? Gear whine is usually caused by something mechanical like wear or pinion angle on the shaft to differential yoke. Like petrock suggested, take a look at the gears and the oil coming out.

 

Thanks for the info. I just got the car so it has been there since I got it.

 

If the rears whinning unfortuantly I oil change wont helo you