kadn33

I have had this whine coming from the front differential - supposedly- since I got the car almost one year ago that will increase with the speed and accelerating, then decreases slightly when releasing a bit of gas pedal but still noticeable.
Replacing the old oil which showed metallic powder with a Lucas 75W-140 oil made it a bit quieter but at 75 mph starts to be annoying again. So I was about to get some Ceratec and add it into the front diff to reduce friction but I saw that line in the product details saying that is not to be used in locking differentials and a further serach brought the Liqui Moly Gear Protect product which can be used in any diff and reduces friction as well. Being confused on what to do I have contacted Liqui Moly and they replied that for my case Ceratec would be the product to use but it cannot be used in self locking diffs that have clutches as these work under a specific friction value - not much of a solution - which brings these questions because my knowledge is zero:

- Is a 75W-140 oil giving a different friction that the 75W-90 and thus not helping in this case?
- Does the front diff in the cayennes use clutches? I could not find any info on this.

Thoughts on what to do next? Ceratec, Gear Protect, change to 75W-90 or forget and be happy? Experiences to share using something else?

fortysixandtwo

All Cayenne front differentials are open, so no clutches to worry about.

kadn33

Thanks for this useful information. I googled for Touareg and Cayenne diffs info and could not determine what they are. Also being my knowledge very limited I might have had the answer in front of me but didn't know.
When I'll back from vacation I'll get it done and report the result. For reference the Liqui Moly tech suggested adding a10% "addressing" dosage of Ceratec since I already have noises.

95_993

Circle back and let us know how it works for you.

ciaka

On cayenne forums I have DIY for changing diff fluids. One needs anti slip. The thread shows what fluid I used. Works great. Nothing needed to add.
Search for cayenne differential DIY or my name threads.

kadn33

Well finally the Ceratec arrived after a long wait and yesterday had some spare time so I added it to the front diff and the excess oil coming out looked good, dark in color but no metallic powder like the old one. Went for a drive and no change, the noise is still there.
Replaced the rear diff oil adding some Ceratec as well and again no luck.
The driveline is smoother specially with new oil in both diffs now but the noise is sitll there so I guess I am looking at a trasnfer case or noisy shaft bearing issue. In any case the DIY time is over until October with the hot temperatures setting in and the noise is barely noticeable at the speeds I usually driive and not getting worst for now.

Dilberto

Front diff needs a higher viz gear oil: 85w-140 Limited Slip. It gets most of the engine and driver weight loads, despite receiving the smaller, AWD drive split....

Vivid7

I just use mobil1 75w-90 in the front. I just changed it at 37,500 miles and the oil was really dark.

oldskewel

For my '04 S at least, and many others I expect, here's the spec from the TSB (and BTW, it is not spec'ed in either the owner's manual or service manual - those both just say to use Porsche fluids):

Same oil in front and rear differentials. (unless locking diff in rear)

Exact spec is Burmah SAF-AG4.

Googling on that you'll find a lot of people saying it's the same as 75W-90.

Either LSD or Non-LSD will be fine in my non-LSD differentials. But see the TSB - for those with a locking rear differential, there is a different oil.

PO put in Redline 75W-90, so I'm happy to stay with that. No problems.

19psi

Where did you find that viscosity recommendation and can you post a link to it? Is it an updated TSB from Porsche? Burmah SAF-AG4 cross references to 75W90 according to manufacturers such as Red Line. Also why limited slip as Cayennes don't have "posi traction" front diffs with clutch packs?

How does the differential support any weight?

JAGMAN1

I'm running Redline 75-110. No change in noise from the normal Redline 75-90. Slight hum at 49 and 70 mph.

kadn33

I went for the Lucas Oil 75W-140 in the front diff thinking that because of the higher temperatures during summer in the Middle East it would help to have a thicker oil and if this was not stopping the noise it would avoid any further damage perhaps but because there was no change at all I went with the 75W-90 in the rear.
Again, I will leave it there for now because of the temperatures starting to raise and also the fuel pumps stepped in asking for replacement as well.

Let's think positive and be happy of all I am learning from sorting out the car

tats

Had a slight front diff noise on my 957 GTS - added Nulon G70 and disappeared. Ymmv.

Dan87951

I have been using Mobil 75w90 for years and have almost 40k on the fluid, and the diff is church quiet. I'm getting ready to do my second drain and fill.