Current mileage: 13k
Trackdays: 5+ hard ones
Daily driving: Light/Easy

around 11k miles I started to hear a hummm or Grrrrr noise from the rear diff when making sharp lowspeed turns. I figured it was time to change my diff fluid because of the hard trackdays so I did so, at about 12k, with Mobil Gear oil 75/90 I think, the one that everyone recommends. I used 7/8ths of the bottle.

The noise was immediately gone after the change, so now I'm a happy boy. However now after about 1000 miles after the change I'm starting to hear the noise again, not as loud as before, but its there for sure.

Is this a normal noise? Did I wait too long to change the fluid the first time after hearing the noise? Did I damage my diff?

Any thoughts from you experienced guys would be great!

Thanks!

Dave

 

How loud is the noise? It is probably normal...

 

Sharp low speed turns will cause diff grumble or grrrr or humm.
Normal.
The diff wants to "lock" because of the speed difference between left & right but it can't because of the grip.
Grumble

Why did you pick the Mobil SAE 75W-90?
Doesn't your manual state to use a straight SAE 90?
First choice (in your climate and in any other then the one mentioned below ) = LE-607.
Second choice (in really REALLY cold climates) - Amsoil 75W-110.

 

Its audible... like if your passenger was humming to music. Its not loud, but you can hear it.

 

Thanks for the input!!

I picked the Mobil 1 75/90 because it was used it many writeups in the DIY section here in the Under the Hood forum. Xviper and many others said it was good for most, so I followed suit.

I understand what you mean about the diff... cause the inside and outside wheels are spinning at different speeds.


I guess its normal.. this is my first Rear drive car so... I'm still learning!

 

if it is normal, i'm curious as to why it went away after a diff oil change.

 

AP2_S2K Posted on May 9 2007, 08:09 PM
Then also learn to read your manual

xviper used that oil also because of the low temps the car has to be started & used in and yes he has gotten good results with it.

Your own experience with the 75W-90 are different, aren't they?
Your diff starts making "noise" again after 1000 miles.
Learning opportunity
Get yourself a bottle of LE-607.

 

So if I get some sort of grumble/grr/hum noise in a straight line at low speeds, my diff is about to go? This noise is only audible with the windows up and is very faint.. I won't be able to check the fluid until this weekend

 

tekstar Posted on May 9 2007, 11:04 PM
Don't forget the diff is close to where you're sitting.
Not a lot of steel and insulation between you & the diff.
Some "faint noise" with a 2001 car is probably normal - hard to tell online.
Go to a local meeting and ask experienced owners their opinion.
Read your manual's recommendation on diff oil again.. and again... and again

 

Thank you so much!