Author Topic: Power Steering Fluid (Read 5377 times)

Sarstan · « **on:** November 11, 2009, 02:56:22 PM »

Hi everyone. I've got a '91 318is. I finally cleaned the cap of the power steering reservoir and noticed it states ATF oil. I did some googling about it and all, but nothing states about having regular power steering fluid it in. I currently have power steering fluid inside and wanted to know if mixing the fluids would cause an issue or if I need to drain the old power steering fluid?
I've been driving with this situation since purchasing the car. The only real problem I have is when I get to the extremes of turning it likes to squeal. That in mind, clearly regular power steering fluid works, but I have a feeling it's not going to last forever like that.

monty23psk · « **Reply #1 on:** November 11, 2009, 03:01:37 PM »

Yes, ATF is what all BMWs used for power steering. Drain it and replace. Regular PS fluid will ruin your pump faster as it will overheat due to the properties for the PS fluid. I use Dexron 3 ATF.

Sarstan · « **Reply #2 on:** November 11, 2009, 03:21:33 PM »

Would mixing the two be a problem? I was also thinking of doing the lazy way of draining it. Suck out what I can, fill it up, suck out again, etc until it turns a lovely red.

monty23psk · « **Reply #3 on:** November 11, 2009, 05:57:24 PM »

Mixing would be bad. That method is better than not doing it, but would take a long time and about 4 or more quarts at $5 ea. Buy a six pack at $6 bucks and dont be lazy, just remove one hose or actually loosen it until fluid starts to come out from the bottom where it connects to pump and go get a beer. After the second beer, tighten it and refill. This way you would get most of it out.

DesktopDave · « **Reply #4 on:** November 11, 2009, 06:33:00 PM »

I thought they were both hydraulic fluid? I'm not sure of the difference though. Sounds like good advice though. I'll bet you'd be OK either way, but I'm not known for being easy on cars...

It's not difficult to drain the system...just messy. Crack the lower bolts on the rack & drain them. Move the steering lock to lock five or ten times to force out most of the rest.

I'm sure there's a reason why BMW put ATF in their reservoirs and the rest of the world doesn't. I have no idea why, but I've been curious about it for years. Crazy Bavarians.

monty23psk · « **Reply #5 on:** November 11, 2009, 09:41:23 PM »

Deals with viscosity of the fluid and the internal components for the pump and rack. Also cooling properties. Old bmw didnt even have racks and pinion, just had steerring racks, which were heavier duty, like diff.

Sarstan · « **Reply #6 on:** November 21, 2009, 02:24:51 AM »

Wish I drank so your full advice would do well for me, Monty, but I do see the point of why I should drain it properly. I have been lazy recently anyway, so I guess I should correct that and do this right. I was hoping to change the transmission fluid, but again since I'm so lazy I haven't located either the drain or the fill spot.