Power steering fluid for 1960's cars (specifically Mopar)

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Is there any credible / authoritative information as to what to use (or what to avoid) when it comes to power steering fluid for old / antique / classic cars? I'm specifically interested in 1960's Mopar, I have no idea if other brands used different materials for hoses and gaskets and seals that would point to different solutions.

As far as I can tell, besides ideas about the wrong fluid with the wrong additives "gumming up the works" (not that the works in these pumps and steering gears are all that complex), there are concerns about the wrong choice causing leaks where there were no leaks previously. And then all the usual concerns about viscosity, high temperature tolerance, "frothing", etc.

I suppose there are boutique brands of PS fluid marketed for old / classic cars, maybe with solid tech specs behind them that proves they are the way to go vs commonly available retail choices?
 
If I'm not mistaken they'd use anything. Down to 10w motor oil as well. Sometimes hydraulic oil but usually ATF. Truth be told it matters little. I wouldn't sweat using regular modern power steering fluid as it's pretty universal. Could use about any atf as well. And the comparability with seals and hoses is non existent. The foaming or frothing as you say is also a non issue. What they had back then is what they had available. Not because it's best. Given modern choices they'd have gone nuts for it.
 
It's been almost 30 years but 100% my '68 Charger definitely used and the shop manual called for ATF.

Sorry, its been so long; I want to say Dextron/Mercron [GM] type... Were talking early/mid 90's, as I recall there was F-type, Dextron/Mercron (SP?) and generic ATF (Additionally, I recall "Power Steering" fluid sold in little ~6 oz bottles intended to be used for top offs. That stuff was thin and clear like brake fluid, probably some kind of cheap hydraulic fluid). Not sure what would happen if you used the Ford Stuff in a Mopar system??? IDK, but 100% I used some generic and top off PS fluid in the day.

Now that thing tore up parts to no end and trying to use it as my daily driver did not help. EVERYTHING [except the long block]; you name it; it broke. The steering gear box leaked like a sieve, so I drove it about a year dry (No P/S). I'm sure that didn't help, but the parts were already tore up so... When I got the coin, I bought a reman steering box ($$$ at the time) and a cheap (Trac Auto) reman P/S pump. I recall going thru several of those cheap reman PS pumps in the next year or two... I went thru bins and bins of other vehicle hoses to find something that would work (Today, you probably have them made to spec I guess). I distinctly remember having many P/S leaks around the fittings; chasing the threads and swapping out hoses helped, but they blew out more than once and weeped often (Again, quality of the parts used was questionable).

Best of luck to you
 
I found a 1968 Plymouth service manual online that says "replenish with hydraulic fluid specially formulated for minimum effect on rubber hoses. Such a fluid is available under Part Number 2084329, Power Steering Fluid."

1968 Plymouth Service Manual
 
I found a 1968 Plymouth service manual online that says "replenish with hydraulic fluid specially formulated for minimum effect on rubber hoses. Such a fluid is available under Part Number 2084329, Power Steering Fluid."

1968 Plymouth Service Manual


Were there ever ASTM specs for PS fluid published back in the 60's so at least it might be possible to track down modern equivalents?
 
The following is from:


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Mineral-oil based universal power steering fluids are usually suitable for any of the following: Applications that specify Dexron, Dexron III, Ford Mercon, Ford M2c-138CJ or Type A ATF fluids. This includes most domestic makes (Chrysler, Ford & General Motors) from the 1970s through 1990s, and U.S.-built VW models from 1984 to 1989.

Mineral-based universal power steering fluids are usually NOT recommended for applications where special fluids are required such as most 1990 and newer European and Japanese PS systems. Most of these require some type of synthetic-based power steering fluid.

Synthetic-based universal power steering fluids are usually suitable for applications that have the following OEM specifications:

American Motor Corporation C 4124

Chrysler MS-1872; MS-5931 & MS-9602

Ford M2C138-CJ; ESW-M2C128-C&D; M2C195-A; M2C204-A & M2C33-F

GM/Saginaw PSF 9985010; 9985835 & 89021184

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Regarding my specific question about 60's MoPar's, I can find no "MS" spec older than MS-1872:

MS-1872 For Chrysler, Dodge, Plymouth vehicle built prior to 1989. Replaces Mopar Part # 4318055

There is also MS-5931 which is described along with MS-1872 as amber or clear in color.

A new dimension to this rabbit hole is the apparent fact that some of these PS fluids were based on mineral oil, seemingly the older MS-1872 and possibly MS-5931 and also possibly or probably the original PS fluid used in the 1960's.

So a new question comes to mind - should I be looking for a mineral-oil based PS fluid?
 
As others have said, either a dedicated PS fluid or a Dex/Merc ATF will work fine.
 
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