Noisy Differential

[97LT1Z28]

I've been hearing a howling noise coming from the rear of my car. It's consistant with the speed I'm driving. After spending lots of time troubleshooting, I've narrowed it down to the differential. It's not the tires or the brakes for sure. I'm hoping that a good fluid change will quiet it down.

My question is: Do you have to use GM PART #1052358 (a limited slip additive) along with the 80-90W gear oil or should I use the gear oil by itself?

[z28_xxx]

your fluid level is either low or your gears are messed up due to a bigger clearance between them

the slip additive will keep the 'chatter' of the diffferential gone

you might want to try a heavier oil if the 80-90 doesnt work..like 90-140 or so

I've been hearing a howling noise coming from the rear of my car. It's consistant with the speed I'm driving. After spending lots of time troubleshooting, I've narrowed it down to the differential. It's not the tires or the brakes for sure. I'm hoping that a good fluid change will quiet it down.

My question is: Do you have to use GM PART #1052358 (a limited slip additive) along with the 80-90W gear oil or should I use the gear oil by itself?

[Trash man]

a howl? sure it aint a bearing? mine howls the same at any speed, accel and decel. put it on jack stands, have some1 turn the wheels and listen for a noise

[dochidalgo]

The additive "is a must"....I've found out that the Mopar's is as good as ACDelco's, even better (the Dodge Viper uses it too), sorry I have not the tech article about this matter right now.
Your car needs the 80-90W gear oil GL5, not the GL4, there is a difference in the formula.
Take care
Dochidalgo

[Joe 1320]

I've been hearing a howling noise coming from the rear of my car. It's consistant with the speed I'm driving.

Typically the sound of a pinion bearing on it's way out. Fix it quickly or the ring and pinion will not be far behind.

[Stroked68Vert]

Howling from rear

My 99 started to howl at 65,000 miles. Finally took it to a good rear end place. They said that 10 Bolt is weak especially in axle bearings. Replace the left bearing and scorred up axle with Moser unit and now I am howl free!!!

In any case have someone look at it before you guess.

[97LT1Z28]

Thanks everyone - you always come through!

[SS_CarGuy]

If the sound changes with acceleration or deceleration, then it's the ring and pinion gears. If its a constant howl that changes pitch with speed but never goes away, then its a bearing. And I am with Joe on this one...it's most likely your pinion bearing and you better get it replaced before you seriously damage your differential.