replaced PS fluid with ATF, "heavier" steering

[akela]

Hi all, it's my first post on this great forum.

I have recently changed PS fluid with ATF (using "turkey" method) in Buick Century 2002. Did it because the old fluid (presumably the factory fill) was dark.

Noticed that steering feels somewhat differently now. The wheel feels little "heavier", especially when being turned fast.
Although I can't say the power steering not working properly, or that it become worse than before. I can still turn the wheel with 2 fingers. But it certainly feels differently.

Just curious, what could be possible explanation for this? Is viscosity (or some other properties) of ATF are that different from PS fluid?

 

[hate2work]

to bitog-


I think you were supposed to use an actual PS fluid in your system. Not sure what the real difference is, viscosity could be one difference. I recently did a complete PS flush, it was so easy I'll never do another turkey baste/refill. It doesn't take much fluid, do a search and you'll find some write-ups on how it's done~

 

[willix]

ATF although widely used these systems GM recommends to use a spec. PS fluid for the variable effort function. You can get a gallon for $12.99 at O'reilly and is easy to find most parts houses.

 

[akela]

thanks for the replies.

I understand that GM recommends PS fluid, and can change it, no problem. But I want to understand what is wrong with ATF exactly?

The viscosity (for both 40C and 100C) seems to be around the same (35...40 and 7 respectively). Rubber swelling properties perhaps?

 

[willix]

I was lead to believe the it could cause leaking & may mess up the valving in the rack. The rack is a $500 piece + labor bringing a rack repair up $800+. Not unlike you I was skeptical and searched longer than was abosolutely nessesary for facts and this was the rational.

 

[Gary Allan]

While some cite potential seal compatibility issues, I've yet to see a bona fide seal failure when swapping from a PS fluid to an ATF with a perfectly good system.


Any/all of my ps systems get AMOIL's ATF in them regardless of the OEM spec.

 

[mechtech2]

You old fluid may have been thinner after it was beat up.
When new, who knows?

 

[Gary Allan]

If it was just viscosity loss due to shearing, one would reason that the same condition would be present with the older fluid at lower temps.

Maybe it's the improved/refeshed/advanced anti-foaming properties that are making the difference.

 

[akela]

That makes sense.

8-years old stuff, dark-colored... it has probably not too much in common with GM part No 89020661.

 

[countryboy9799]

I used amsoil's PSF, wasnt much more expensive than the ATF.
Did you ever get it cleaned up? Mine got dark again shortly after, some here suggested it was getting the color from the hose.

 

[Nick R]

I had somewhat similar issue, but in reverse. I changed the original PS fluid with Maxlife PSF, and the steering was TOO light. Added a quart of Mobil 1 ATF, didn't make much difference. Added a bottle of Lucas PS stop leak, and it is perfect. I,d just add a quart of regular Power steering fluid.

PS: Power steering fluid, and Mobil 1 ATF smell AWWWFFULLLL.

 

[akela]

Originally Posted By: countryboy9799
Did you ever get it cleaned up? Mine got dark again shortly after, some here suggested it was getting the color from the hose.
well, I did TB 5 times, allowing 1-2 days inbetween. Now it looks like ATF is supposed to look, i.e. clear and red.
Done it 3 weeks ago, so it's too early to tell how fast will it get dark again.

 

[pbm]

My 2002 Century turns the fluid dark rather quickly. Did you have groaning and squeeling before the change?

 

[TooManyWheels]

As another data point, I recently had the PS pump in my 97 Chevy pickup replaced, and the mechanic used some sort of clear fluid which I assumed to be actual Power Steering Fluid.

Unfortunately, there was little to no assist at low RPM, when you need it most. Changing to Amsoil ATF made the power steering useful again.

 

[akela]

Originally Posted By: pbm
My 2002 Century turns the fluid dark rather quickly. Did you have groaning and squeeling before the change?
no, I didn't notice any unusual sound. The dark color of the fluid was pointed out by the technician guy at the quick-lube place. At home, I verified that he was right about the color, grabbed couple of bottles of cheap generic multi-vehicle Dex III compatible ATF, and turkeybastered it myself.

 

[countryboy9799]

The amsoil PSF I used it pretty light in color so that maybe makes it look worse. My steering has always worked fine with no problems.

 

[willix]

It did the return line method a 2 man operation and went thru a full gallon almost of supertech dex.
The fluid was very black that I replaced because of the growning symptom.
ATF did stop that and I put another 1000mi on it before replacing the new ATF w/GM spec fluid that is pretty much a universal fluid shared amongst several car makers. Nothing unique about this PS fluid at all.
I was perfectly fine w/ATF in there but some were convincing enough at portraying this as a forbidden practice w/dire consequences.

I am not totally convinced of the requirement for this variable effort p/s application.

 

[Audi Junkie]

Complete flush is the only way to go in an old system.

 

[onion]

I've been using ATF in my GM vehicles for several years now. No problems to report. In the past I've done turkey-baster changes with Mobil 1. Lately I've been using Dex VI because I have a stash of the stuff to use up, and I don't like how it shifts in one of my vehicles (and I'm suspicious of how it's performed in the other... haven't checked up on that though).

 

[OVERKILL]

Originally Posted By: Audi Junkie
Complete flush is the only way to go in an old system.


Gotta agree based on my own experience recently (as I'm sure you'll remember) and the results with a full flush vs those without.