PS fluid consensus
 

The BMW OEM power steering fluid is ATF, probably a German brand, like Pentosin, which is not readily available.
Reading through other forums, nobody really knows if regular synthetic ATF is OK, or if it needs to be Dexron III or Mercon V ATF.

If you would use any brand of synthetic ATF will the power steering seals deteriorate or not? If it's a "regular" Mobil synthetic ATF will it be OK? Or does it need to be Dexron III or Mercon V compatible?

RedLine ATF

+1. That's what I use on all of mine.

Vipers, Vettes, BMWs. They all get RedLine in the Powersteering systems and I've never had any leaks or failures.

Hopefully the link to this PDF will work for you...it was the last list I got that was up to date as of 11/2009 which lists the multiple brands recommended by BMW for power steering systems.

Your X5 would fall under "3.0" (which says to look at the table of brands under "5.0": http://bimmerboard.com/members/q/ori...0Type-List.pdf

Redline D4 is my choice too ( it's what I had leftover from the trans filter project )

:)

I used Mobil 1 ATF in my PS reservoir, no problems!

I've been using Mobil 1 ATF on my annual PS fluid change (turkey baster method) for nearly 7 years now without issues. No leaks or noises. I think I even use some Honda ATF a couple of times without issues.

Concur... Mobil 1 ATF... No Problems.

CHF 11s if your reservoir is so labelled. ATF otherwise. No mixing, they are not compatible.

If ATF, I would use any Dexron from any reputable major brand. Or Mercon. Not a synthetic, as what is already in there isn't a synthetic. There is no reason to hunt for a special ATF, in this case it is being used only as a hydraulic fluid and the ingredients added to different ATF fluids for different specs are essentially irrelevant in a power steering system.

Thanks for all the answers. ATF is written on the canister. But there are numerous ATF's.
I have 2 different Mobil 1 ATF's (about 3 qt each). Which can I use, or it doesn't matter?:

http://i380.photobucket.com/albums/o...psd3a250fb.jpg

So here is the description of the grey bottle:

http://i380.photobucket.com/albums/o...ps11ce2206.jpg

And here is the description of the blue bottle:

http://i380.photobucket.com/albums/o...psa777eb7c.jpg

The grey bottle appears to be the older label of the Mobil 1 ATF that I used. I haven't seen that bottle on the shelf for at least a couple of years. This is what's currently on the shelf => ATF | Mobil 1™ Synthetic ATF

It just doesn't matter.

I was checking the powersteering fluid on the x5 and it is at the lower mark. Figured I will add aft fluid to what is in it already. My question is I don't know what kind of fluid is in it other then it is atf. The other concern is I can not tell if it is synthetic or regular. No burnt smell at all and it looks like it it is a reddish brown. So my question is can I add synthetic to what is in it? Also I can't find dexron 3
They had valvoline maxlife
Advanced auto brand
Castrol domestic multi vehicle
Attached are some pictures

Pict 2

I've recently switched from whatever red fluid was in the reservoir to Pentosin ATF which is gold colored and that's because I had a few quarts laying around from my E39 tranny job...no issues so far...I need to order some more from FCP and keep changing it every month or so to make sure all the old fluid will be out...

FYI,

Local NAPA store carries Pentosin CHF-11S for about $19/qt.
This is what I use.

Personally, from my research, Pentosin CHF-11S is a thinner ATF fluid and that is all. Many people use Mobil 1 ATF (in a system specified for Pentosin) w/o any issues at all. This is well documented in other BMW, Mercedes, Porsche, VW forums where people use Mobil 1 ATF instead of Pentosin.

As long as it is labelled ATF and not CHF11S you can use any ATF. Make sure it is fresh. I would pick one that is Dexron certified but only to make sure it is blended to some quality standard. It doesn't need to be synthetic. What is in there isn't, so no reason to mix types.

I used Mobil 1 ATF with no issues.

Check the hoses on bottom of reservoir to be sure they aren't leaking (they tend to weep at the crimps with age)