So right before I purchased my V in August, my sales manager replaced the differential.

Ive had the car for about 1 1/2 months now, and I wanted to change out the diff fluid just to be on the safe side. I get the car back from the dealership a couple of days ago and it seemed fine...

Now when I drive it, I hear this low pitched sound coming from the diff. Its only when Im driving slowly in 1st, and it is particularly noticable making tight turns (into parking spaces and such).

Anyone have any ideas?

The moan is the posi, make sure the anti friction additive was put in. Or do your own rear changes and youll know its done right.


F

They didn't put the posi additive in. I just had a new rear put in mine and before I left the lot I looked at the bill and saw that they only billed out two bottles of lube and no additive. I raised hell and they put the additive in.

Yep, you need the additive. Your diff is fine, just needs a little more of the slippery stuff.

Why even use the overpriced gm crap. Put in REDLINE or ROYAL PURPLE fluid it already has a additive built in and is a far superior lubricant!!! You can find it at a lot of speed shops for half the price of the gm crap!!:thumbsup:

So right before I purchased my V in August, my sales manager replaced the differential.

Ive had the car for about 1 1/2 months now, and I wanted to change out the diff fluid just to be on the safe side. I get the car back from the dealership a couple of days ago and it seemed fine...

Now when I drive it, I hear this low pitched sound coming from the diff. Its only when Im driving slowly in 1st, and it is particularly noticable making tight turns (into parking spaces and such).

Anyone have any ideas?

The exact same thing happened to me. I took the V in to have the fluid changed in the rear as a preventative measure and not long after the service the rear started making noises. I found out that the procedures the dealer uses does not have them add the friction additive, they say it is because they use synthetic fluid that it does not need it. I call BS on that and did the research and found the procedures and parts list on the net and take it to them. They apologize and replaced the rear just to be safe and add the additive in the new rear.

Why even use the overpriced gm crap. Put in REDLINE or ROYAL PURPLE fluid it already has a additive built in and is a far superior lubricant!!! You can find it at a lot of speed shops for half the price of the gm crap!!:thumbsup:

What fluid exactly from Redline?

Can you use their MT-90 in your tranny?

What fluid exactly from Redline?

Can you use their MT-90 in your tranny?

Royal Purple synthetic oil is just as good. Luckily, OReilly auto parts stocks Royal Purple, if you have one close by I highly recommend going that route.

Have them check the axle bearings. If they are blown the whine will be very bad.

What fluid exactly from Redline?

Can you use their MT-90 in your tranny?

You can use Redline's 75W90 for the rear and it already has the limited slip additive mixed in. Don't get the 75W90NS as it does not have the additive.

For the trans use their D4 ATF. It's a Dexron III ATF specially formulated for manual transmissions that specify ATF.

John

You can use Redline's 75W90 for the rear and it already has the limited slip additive mixed in. Don't get the 75W90NS as it does not have the additive.

For the trans use their D4 ATF. It's a Dexron III ATF specially formulated for manual transmissions that specify ATF.

John

Thanks John. Think I'm going to change out the fluids myself this weekend.

......I took the V in to have the fluid changed in the rear as a preventative measure ......

I still am not on board with this thinking.

There's no reason your diff fluid will break down and need replacing unless it gets contaminated (i.e. with water).

Don't futz with it!

I agree 100%. I haven't bothered to check the maintainance schedule for the diff fluid, but I'm sure it's something like 40k or 50k miles. 14k miles now and no whine for me.

Guess it's another pat on the back for leasing the car. I'll be handing back the keys to GM right when the warranty is expiring. No reason to waste my money on preventative maintainance that isn't OEM spec'd.

I still am not on board with this thinking.

There's no reason your diff fluid will break down and need replacing unless it gets contaminated (i.e. with water).

Don't futz with it!

Or metal. Mine had lots of it.

If your differential is shredding itself, a fluid change isn't going to do much one way or another.

If your differential is shredding itself, a fluid change isn't going to do much one way or another.



Reduction in friction = reduction in shredding... :cookoo:

At what point do you think you're getting an increase in friction? 3,000 - 6,000 - 12,000 miles?

Is that why you think it's shredding?

Changing your differental fluid for no good reason only adds other unwanted potential variables like overfilling, underfilling, wrong fluid, no additive, wrong additive etc........

Have you read this thread rbrown?

At what point do you think you're getting an increase in friction? 3,000 - 6,000 - 12,000 miles?

Is that why you think it's shredding?

Changing your differental fluid for no good reason only adds other unwanted potential variables like overfilling, underfilling, wrong fluid, no additive, wrong additive etc........

Have you read this thread rbrown?

Have you? This is my thread :)

Touche. :)

I'm more refering to darkknight's post on your thread.

The exact same thing happened to me. I took the V in to have the fluid changed in the rear as a preventative measure and not long after the service the rear started making noises.

I found out that the procedures the dealer uses does not have them add the friction additive, they say it is because they use synthetic fluid that it does not need it. I call BS on that and did the research and found the procedures and parts list on the net and take it to them. They apologize and replaced the rear just to be safe and add the additive in the new rear.

I find it sad that people feel apprehensive about taking their V to the dealer to have the fluid changed. This car has to be one of the easiest to change the rear fluid on. Just remove the drain, let it empty, refill with proper fluid and you're done. No removing the rear cover like a lot of cars.

A rear end fluid change is more simple in this car than an oil change. If you can't trust a dealer to do that, I wouldn't take my car to them for any type of service or warranty work.

GM used to recommend a rear fluid change at 7500mi for all posi rear ends. The fluid change was to remove all the clutch material and metal particles in the fluid from break-in. They may have removed the requirement for the fluid change, but IMHO it's still a very good idea. For less than $18 and 30 min of my time, I have good quality clean fluid.

John

Its even easier when someone has pictorial instructions on how to do it!

CTS-CTS-V FAQ: Differential Lube change procedure (http://www.cadillacfaq.com/faq/answers/difflube/index.html)

THANKS STEALTHV!

Reed

Its even easier when someone has pictorial instructions on how to do it!

CTS-CTS-V FAQ: Differential Lube change procedure (http://www.cadillacfaq.com/faq/answers/difflube/index.html)

THANKS STEALTHV!

Reed

Yes... Cadillac FAQ FTW!

Reed deserves more points than he's got.

Give him some points!