Getting ready to do fluid change on the front and rear differentials on my 05 CTT and just wanted to get final advice on fluid.
Have been searching and found that changing with Mobil 1 synthetic 75W90 gear oil would be good. Just wanted to run by as last sanity checkbefore I get going. Will greatly appreciate this last minute confirmation.
If you can also give me pointers on location of the drain plugsd on the front and rear, it would be great (will look up in manual too but if you already know the location and can share thee info it would be awesome).

Thanks.

 

Does this have the proper friction modifiers for a LSD? (If you have it)

 

How do I tell?
In the window sticker for car it said something about 2 way locking diff...or something like that
Inside the car I do have the slider to change from highway, to lock rear/all, to mountain mode. Ring any bells?
Thanks for the help in advance

 

The type of diff oil used and directions on how to change it is not included in the owners manual. Curiously enough, a few other technical documents fail to list the specific type of gear oil used. With that said, there are not many gear oil options available for this application on the market- most use 75W90. Considering Porsche uses Mobil fluids, Mobil 75W90 sounds right to me.

In regards to the friction modifier, it is an additive that is needed for limited-slip and clutch engaged differentials to work properly. It is better to have the friction modifier and not need it, then not to have it and need it. As such, most gear oil will have these additives. Just look on the label for something to the effect of "friction modifier additive" ,"LSD" or "limited- slip approved".

You will also need a pump or fluid evacuator to change the oil properly.

Here are the instructions on how to change the rear diff fluid. For your application, it will take 1.4L of oil to refill.

Post pics and share with others if you get a chance.

 

I had to grind down an allen wrench to fit the front diff drain plug. The clearance was minimal between it and the frame/rack.

 

Here is the gear oil i want to use:
http://www.mobiloil.com/USA-English/..._75W-90LS.aspx

So do i take it that i can use this same oil in both front and rear diffs?
If yes, i will try to do next weekend or so.

 

This is a pic from the rear of the car (looking towards the front).
Can you confirm that this is the rear differential, and #2 is the drain plug, and #1 is the fill plug


1 - fill plug
2 - drain plug


Want to confirm before doing the job. Thank you yet again.

 

Looks right to me.

One worked of advice. ALWAYS make sure you can get the fill plug out first!

 

Roger that.

 

OK. I did the rear differential fluid change. Will post a dyi for this forum in case others are looking for info on this.

 

Thank ciaka for posting the DIY. I am doing this next. Please post one for front when you do it please