# What type of fluid to use for Power Steering on E39



## Mz3bo (Jan 19, 2003)

Hi, I just wanted to make sure I am getting the right fluid. First, my bmw dealer is too far from where I am so it explain why i won't be getting BMW fluids. Now, what kind of fluid should I use for the powersteering in a 97 540I. However, on the little black cap, it is said ATF fluid, while the reservoir is for power steering. Should I use Automatic transmission fluid ???

Thanks


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## Steve D (Oct 10, 2002)

I use a good quality synthetic DexronIII fliud like Mobil one.

Steve D


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## Mz3bo (Jan 19, 2003)

Alright.. but is that fluid a Automatic transmission fluid or Power steering fluid ??



Steve D said:


> I use a good quality synthetic DexronIII fliud like Mobil one.
> 
> Steve D


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## Steve D (Oct 10, 2002)

Dexron III is an automatic trani fluid which is what is specified for the power steering in my 540.

Steve D


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## kowached (Jun 20, 2003)

*You can take your PS fluid service one step further, if you want.*

*Power Steering Fluid*
PS fluid is just like any other fluid and it breaks down and gets contaminated with time and needs to be changed as a preventative measure, unless you think that its a "Super Fluid" and impervious to the elements like no other fluid that I know of. I can not believe that auto manufacturers continue to ignore this fluid in their list of regularly scheduled maintenance, maybe they like being paid to replace PS racks and pumps? I know that bearing clearances inside modern PS pumps are incredibly tight (a particle of anything in the right place could burn it up) - plenty of reason to keep new clean fluid in there. Although, I'm sure the reason that it's not part of the normal OEM maintenance schedule is the likelihood of sloppy mechanics introducing some contaminants into the system, or starting the car with no/low PS fluid, etc... So, the big picture risk of having issues is probably much lower if they just say to leave it alone. So if you choose to do this service take extra precautions and make sure that everything is clean (like you would for a transmission fluid service).

If you are starting with a new car, when performing an oil change service (every 5000 with synthetic) draw the fluid out of the PS reservoir and replenish it with new PS Fluid. By continually doing this you should have clean PS fluid forever and probably will never have to flush the system in this car because this service was started very early on the car.

If this hasn't been done on your car since day one, you might want to do what I did with my car. I changed the PS fluid in it by drawing the fluid out of the reservoir with a simple turkey baster and replacing it with new fluid (good synthetic ATF for this car). I did this once a day for about a week when I got home from work, and used about a quart and a half of new fluid total. You could do this all in one day if you wanted to, the key is to exercise the power steering in between draining the reservoir, and I was in no rush. I figure that I changed about 95% of the fluid this way, and it still looks ruby red. Also when performing an oil change service (again every 5000 with synthetic) I draw the fluid out of the PS reservoir and replenish with new ATF, the old ATF gets added to the waste engine oil and recycled. By doing this I hope to have ruby red PS fluid forever and probably will not have flush the system again.


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