Which atf fluid for bmw 2001 330Ci power steering? I know it's crucial to use the exact one when adding to a transmission but does the standard Valvolene Mercon V or such work for topping up the power steering reservoir?

You should be able to use most Automatic Transmission Fluids (ATF), although if you have a manual shift car, then there is no ATF.
Check the fluid level careful if you do have an ATF container, since it is very rare that you would lose fluid from the transmission.

When the hood is popped, look for a cap that says ATF Fluid only. That is actually the power steering reservoir and not the transmission fluid fill location. I would recommend Dextron III or Dextron VI fluid for the power steering. Don't use your average power steering fluid, it says to only use ATF for a reason.

bmw uses ATF as power steering fluid most likely one of the hoses are failing and will need to be replaced if u start to hear a buzzing noise when turning try not to drive vehicle that can burn out the pump but add fluid before you drive it again the resovor is a dark brown or black round canister with a black lid check the fluid in that if its low then you know its the power steering leak if not then it could be a trans. fluid leak if u have a automatic hope this helps you

Do you mean that there is a plastic bottle of ATF sitting loose under your hood? Or are you asking what the black reservoir with a knurled cap that is full of ATF is for?
If you are asking about the reservoir that is part of the car, it is the power steering fluid. Car parts stores will try to sell you fluid in bottles that say Power Steering Fluid, but your car uses Dextron ATF which is the same thing only it is cheaper when you buy ATF by the quart rather than PS Fluid by the pint.
If you have a bottle of ATF, someone probably put it there so it would be handy when they needed to top off the power steering reservoir. Topping off the power steering reservoir is a routine exercise on many BMWs because their power steering hoses tend to leak.

NO, NO, No, Use regular ATF in the car, this is what it was designed for, read the manual if you still have it. If you start using power steering fluid with the atf the came in the car it will eventually turn into a mud type liquid and sooner than later fail...If you have done this you will need to drain the fluid out replace with fresh atf, run the system in for a quick 15-20 min drive then drain and refill again...

I know E46's use ATF (Automatic Transmission Fluids) for their power-steering systems. BMW Reccomends to use a common Dextron III / Mercon Automatic Transmission Fluid.

Use only a Dexron-III Automatic Transmission Fluid to top off the power steering reservoir. BMW uses ATF instead of power steering fluid.

Hi,
The ATF stands for Automatic Transmission Fluid which controls your power steering. You might have observed your steering has gotten a bit more stiff... or will eventually get to this. This ATF is different from the hydraulic fluid which controls your brakes. You need to take it to a BMW automechanic who would top it up. It is sold in containers like hydraulic...you will buy it and give it to mechanic for refilling. The container for this is in the bonnet just below the windscreen almost at bottom of engine. also ensure that the lid is not open and the container is not broken in any way to leak the ATF

Cheeers

Yes There Is ONLY ONE PLACE for Power Steering Fluid.

ZF Gemmer Steering

The ZF Gemmer steering is permanently filled with oil. There is no drain plug.

ZF Rack and Pinion Steering Without Power Assist

The ZF rack and pinion steering is lubricated for its service life and therefore does not require servicing.
In case of repair, steering components on E21 vehicles are to be lubricated with a sodium-based grease, with a temperature range of -30°C to +75°C .
Calypsol D 4024 BMW Part No.32 11 1 116 929

Ball and Nut or Rack and Pinion Power Steering

Only reputable brand Automatic Transmission Fluid (ATF) of Dexron® III formulation may be used for the power steering and power steering pump.
In case of brief hydraulic noise after starting at low outside temperatures, we recommend replacing the red ATF with green CHF or LHM oil (see below).

ZF Ball and Nut Power Steering with H31 System

The approved oils for BMW models with power steering and the H31 brake booster system are identical with those oils approved for power steering without the H31 system except for the following:

E32 models with self-leveling rear suspension and mutual oil supply tank in the engine compartment.
Countries with very low outside temperatures (e.g. Canada) had their power steering systems filled at the factory with Pentosin CHF 7.1 since 9/87 through 9/91. This is also to be used on vehicles built before 9/87.

Since 9/91, vehicles now use Pentosin CHF 11S instead of CHF 7.1.

Pentosin CHF 7.1 BMW Part No.81 22 1 468 879
Pentosin CHF 11S BMW Part No.82 11 1 468 041

These cars are marked with a pertinent label located close to the oil tank.

LHM oils (green color) of the following manufacturers may also be used instead of Pentosin (CHF 7.1):
Shell LHM
Castrol LHM
Exxon LHM

The mixing of CHF, LHM oils and ATF is not permitted.

Pentosin CHF 4548 was used on vehicles built before 9/87 but is no longer available. However, mixing of Pentosin CHF 7.1 with residual quantities of Pentosin CHF 4548 are permiffed in these earlier vehicles. Mixing of these two oils is not permitted for E32/E38 vehicles.

The hydraulic system for power steering and power-assisted brakes must be drained as completely as possible when changing from one type of oil to the other.
All oil supply reservoirs are marked with the type of oil being used - ATF or CHF.

The cap to your power steering reservoir should either say ATF or CHF11s. If it is ATF you can use Dexron automatic transmission fluid. If it is CHF11s the dealer is the only place I know that sells it. There should be level marks on the cap stick.