Power steering fluid

fljeeper

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After replacing the power steering pump on my son's 97 SE. I noticed the field service manual advised against using ATF as power steering fluid. I then did some interweb searching and found lots of support for using ATF +4 as power steering fluid and lots of support for using power steering fluid. So what is the best practice and why?

Thanks,

Dan
 

lowranger

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I would go with power steering fluid..... Because it's says "Power Steering Fluid" on the container. Why not use what is meant to go in there? Just my 2 cents worth.
 
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Mr. Bills

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If I recall correctly, Chrysler changed the Jeep steering system sometime around 2002. Chrysler recommends conventional power steering fluid for Jeeps built prior to 2002. Jeeps built after 2002 can use ordinary ATF+4.

Frankly, most power steering fluids at local auto parts stores are nothing more than ATF, perhaps with different additives but perhaps not.

Even though it may be nothing more than high priced ATF, for your own peace of mind just buy some name brand power steering fluid and call it a day.
 

Drizit

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Jeep used power steering fluid up through 2002, switching to ATF+4 in 2003 and newer TJs.
Yep, when they changed over to the zf box. Apparently from some of the reading I've done you can use ether/or but you have to fully flush the system to switch. Just put back what was in there is my advice.


There must have been a time
when we could have said no.
 

jgaz

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Yep, when they changed over to the zf box. Apparently from some of the reading I've done you can use ether/or but you have to fully flush the system to switch. Just put back what was in there is my advice.

I worked at Chrysler’s Desert Proving Grounds during the time the switch was being considered to use ATF+4 for all vehicle power steering systems, not just the Jeeps. On a number of our power train test vehicles (all models) we ran the steering systems with a 50/50 mix of the std. Mopar power steering fluid and the ATF+4 to test for later compatibility issues in the field. There were no issues what so ever in these vehicles using the 50/50 mix for the full duration of the power train test.
IMO the ATF+4 is a better choice in all respects.

That being said, it sure wouldn’t hurt to get all the old fluid out if you do change over but don’t take a chance on running your pump dry emptying the system. A little left over old fluid in the system won’t hurt a thing.
 

Drizit

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I worked at Chrysler’s Desert Proving Grounds during the time the switch was being considered to use ATF+4 for all vehicle power steering systems, not just the Jeeps. On a number of our power train test vehicles (all models) we ran the steering systems with a 50/50 mix of the std. Mopar power steering fluid and the ATF+4 to test for later compatibility issues in the field. There were no issues what so ever in these vehicles using the 50/50 mix for the full duration of the power train test.
IMO the ATF+4 is a better choice in all respects.

That being said, it sure wouldn’t hurt to get all the old fluid out if you do change over but don’t take a chance on running your pump dry emptying the system. A little left over old fluid in the system won’t hurt a thing.
I bet you have some great info on this topic.
Why do you say atf+4 is better?
Can the older ps fluid systems work with atf?
Is atf better than some of the synthetic ps fluids like royal purple?


There must have been a time
when we could have said no.
 

Jeepcj6

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Just finished putting a rebuilt steering box in Gertie ( no way was I gonna do a seal replacement on a box with 351xxx kms)
so also threw on a filter on the return side.As per the rebuild manufactures recommendations. So being a 2002 with the Saginaw box I went with power steering fluid but the counter guy at Napa googled and it said Atf-4. I did more digging later and found PS fluid as per the owners manual
 

jgaz

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I bet you have some great info on this topic.
Why do you say atf+4 is better?
Can the older ps fluid systems work with atf?
Is atf better than some of the synthetic ps fluids like royal purple?


The only real “info” I have is that there was no compatibility problems with the 50/50 mix I spoke of.

The reason believe the ATF+4 worked better in the applications I had experience with was because the company deleted most, if not all of the PS coolers (or extra loops in the line that served the same purpose) when they started using the ATF+4. This led me to believe the ATF+4 didn’t degrade in the heat like the old fluid. The synthetic ATF also “looked” better when pulling a PS oil sample, post test. (Not very scientific I know but I never saw the oil analyst report)

I have no experience testing any other, older PS systems.

We never tested, or used anything other than Mopar branded fluids.

Sorry I have no other info but I was mechanic and therefore at the bottom of the engineering food chain.
 
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Drizit

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Fair enough, that's still excellent info. I suspect you are correct about atf+4 being more heat tolerant given the temperature transmissions regularly operate at.


There must have been a time
when we could have said no.
 
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fljeeper

fljeeper

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I worked at Chrysler’s Desert Proving Grounds during the time the switch was being considered to use ATF+4 for all vehicle power steering systems, not just the Jeeps. On a number of our power train test vehicles (all models) we ran the steering systems with a 50/50 mix of the std. Mopar power steering fluid and the ATF+4 to test for later compatibility issues in the field. There were no issues what so ever in these vehicles using the 50/50 mix for the full duration of the power train test.
IMO the ATF+4 is a better choice in all respects.

That being said, it sure wouldn’t hurt to get all the old fluid out if you do change over but don’t take a chance on running your pump dry emptying the system. A little left over old fluid in the system won’t hurt a thing.

Thank you for this information. I usually remove the old power steering fluid using a large syringe with a section of tubing attached to reach into the bottom of the reservoir. After replacing the fluid and driving the vehicle, I repeat the procedure.
 

Edosan

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I have a 2005 TJ I bought used so I do t know what kind of fluid is in the system but it is low (at the ADD line in a cold engine). Can I just buy regular power steering fluid to top it off or should I go with ATF+4? Thanks in advance.
 

Mr. Bills

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Although your 2005 should have had the power steering system filled with ATF+4 at the factory, there may be no way to tell what is in it now. Your only clue will be the color. ATF will look red or pink on a white paper towel. Power steering fluid won't.

ATF is a common substitute for power steering fluid and is specified by many vehicle manufacturers rather than power steering fluid. Both are hydraulic fluids, but ATF has additives and friction modifiers specifically for automatic transmissions. I can find no reliable literature suggesting that those additives and friction modifiers are harmful in any way to a power steering system. All of the literature suggests that power steering fluid and ATF is compatible and interchangeable.

If I were in your position I would use a turkey baster or something similar to suck as much fluid out of the power steering reservoir as possible and refill with ATF+4. However, I have an automatic transmission and can use the leftover ATF+4 for that. If you have a manual transmission and don't need ATF+4 for any other purpose you can use power steering fluid if you only need a few ounces and power steering fluid comes in a smaller bottle and/or is cheaper in your locale.
 

JKP

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From the FSM:
1620652610815.png


I have no idea if reg PS fluid will cause harm or not, or if the fluids will mix.