1966 Power Steering Fluid

[Donna G.]

I just bought new power steering cylinder and valve for VB&P and they sent some generic power steering fluid. Of course the manual suggests using GM fluid. What Power Steering fluid should be used - am replacing hoses, cylinder and valve. Thanks

[Joe L.]

Re: 1966 Power Steering Fluid

I just bought new power steering cylinder and valve for VB&P and they sent some generic power steering fluid. Of course the manual suggests using GM fluid. What Power Steering fluid should be used - am replacing hoses, cylinder and valve. Thanks

Donna-----


I recommend using GM synthetic power steering fluid. It's more expensive than generic or other branded power steering fluid but it's what I use exclusively.

1 pint-----GM #12345866

1 quart----GM #12345867

This fluid may be labeled "cold climate" but don't let that throw you. It's fine for ALL climates.

[Jim S.]

Re: 1966 Power Steering Fluid

Here is a paper that I authored several years ago. Although the cold climate power steering fluid is synthetic based, I never heard that it was superior to genuine GM power steering fluid.

http://jimshea.corvettefaq.com/?p=861

Jim

PS Sorry the link doesn't work. I will try and fix it or possibly just copy and paste it here.

[Jim S.]

JIML82@aol.com
PowerStrgFluidRev21MY2012.doc

[Michael W.]

Re: 1966 Power Steering Fluid

Here is a paper that I authored several years ago. Although the cold climate power steering fluid is synthetic based, I never heard that it was superior to genuine GM power steering fluid.

http://jimshea.corvettefaq.com/?p=861

Jim

PS Sorry the link doesn't work. I will try and fix it or possibly just copy and paste it here.

The link works just fine Jim.

[Donna G.]

Re: 1966 Power Steering Fluid

Thanks everyone. Anyone have a favorite place to get the PS fluid?

[Duke W.]

Re: 1966 Power Steering Fluid

I went through this drill about five years ago when I wanted to flush the fluid and change the filter on my '88 Mercedes power steering system. Of course, the MB recommendation is "use MB power steering fluid", which costs about the same as gold dust at the dealer compared to the generic brands at FLAPS, so I embarked on a research project.

Power steering systems are basically hydraulic boost systems, which are common in industrial equipment and aircraft control applications. Chevron has great spec sheets on their various hydraulic fluids, which got me up to speed on the various requirements. Base oils need to have good flow characterisitics at the lowest start-up temperature they will see, and be able to withstand maximum operating temperatures without excessive oxidation. Hydraulic systems in arctic oil fields provide a particular challenge, so synthetic-based fluids are normal, but since our vintage cars don't see extremely cold startup temperatures, a synthetic is not really necessary.

Other requirements include anti-wear and anti-foaming additives.

There were several Chevron hydraulic fluids that appeared suitable, but they aren't readily available in retail auto stores, so I ended up buying a quart of Pyroil power steering fluid at Pep Boys for a reasonable price. From the info on the label and Web site it appeared to meet the requirements, as did other brands. Most said something like "approved by all OEMs", with the exception of Honda.

I never did figure out what's special about Honda power steering systems, but since I don't own a Honda automobile I didn't worry about it.

Five years later the Mercedes power steering system performs as designed, is leak free, and the fluid is still the same amber color with little or no darkening from oxidation.

Duke

[Joe L.]

Re: 1966 Power Steering Fluid

Here is my paper. It doesn't specifically address the "cold climate" synthetic power steering fluid issue. However, you might find it interesting.

Revised : 21MY2012


GM POWER STEERING FLUID

Originally in the 1950’s, automatic transmission fluid (ATF) was specified for use in both General Motors automatic transmissions and also for their power steering systems. But as vehicles got heavier, engines bigger, and temperatures hotter, the requirements for the two different systems changed. The GM Research Labs had a Lubricants Section that began testing and modifying the ATF formulation to improve the performance of the GM Hydramatic, Dynaflow, and Powerglide transmissions. They did this without much regard to the fact that the power steering system was using the ATF fluid as well. Sort of the tail being wagged by the dog.

So around the same time, Saginaw Steering Gear Division and Texaco began testing and developing a fluid specifically for power steering. The fluid characteristics were specifically formulated to provide anti-corrosion and non-foaming qualities with excellent lubrication for year around use. There was also particular emphasis placed on wear testing performance with respect to the vanes, rotor, cam ring, and the driveshaft bushing in the big Saginaw “P” model power steering pump. By the way, the “P” model was the only power steering pump used in all C2/C3 Corvettes and all GM passenger cars and light trucks with power steering in the 1960s and 1970s.

That is why some of the early power steering reservoir caps had ATF specified as the proper fluid to use. All the later pump caps and the owner's manuals have said to use "Approved Fluid". The GM power steering fluid is approved for use in any vehicle with a Saginaw power steering pump.

One other thing to keep in mind: There has always been a big financial incentive for the assembly plants to be able to use one common fluid for both power steering and automatic transmissions. Keeping two similar but different fluids separate in the assembly plants, separate fill systems, separate storage tanks, only one fluid in the field for vehicle service, all are very great incentives. Despite all these obvious benefits GM continues today with different fluids.

To be honest, all of the Saginaw power steering pumps adapt fairly well to all kinds of fluids. The pumps are marketed and sold all over the world and are used by many vehicle manufacturers who specify their own power steering fluids. Chrysler in the past has used a very simple mineral based fluid. They eventually changed to GM power steering fluid. I am not sure if they still use GM fluid today or not. Ford uses a special Ford ATF fluid. VW uses a European brand of fluid called Pentosin. All of these fluids reportedly work well in their vehicles.




I have no idea who formulated the PS fluid that is sold at K-mart, Pep Boys, NAPA, etc. This isn’t to say that it is bad. However, the amber colored GM fluid is the only fluid that has been certified and tested in GM durability test vehicles for millions of miles. It also is the only fluid that have been durability tested in the Saginaw Steering Gear engineering labs for hundreds of thousands of hours. All of the rubber compounds that are used in the seals, hoses, etc in the production GM power steering system are tested in the materials laboratory for compatibility with the fluid.

The GM part number for a quart of power steering fluid is 89020661. The previous GM part number for power steering fluid was 1050017. Both fluids work equally well.

BTW, there is a recent push to use Dex 6 automatic transmission fluid as a “universal” fluid for power steering systems was well as automatic transmissions. Nexteer (formerly Saginaw Steering) engineers report that the Dex 6 fluid does NOT perform as well as genuine GM power steering fluid.

JIML82@aol.com
PowerStrgFluidRev21MY2012.doc

Jim------


The GM #89020661 is discontinued and replaced by GM #89021182.

Also, the GM #12345866 spec fluid is required for 1991-2014 Corvettes. It may also be required for earlier C4. It can be used in any Corvette power steering system.

[Jim S.]

Re: 1966 Power Steering Fluid

Joe,
I think that AC Delco 32 Fl Oz #89021182 is actually GM PS 32 Fl Oz #89020661 under their brand name and part number.
Dexron-VI is 88861037.
I will try and contact the current fluids project engineer at Nexteer and try to get some more info on the subject.

Possibly not a lot of emphasis on hydraulic power steering systems with electric power steering becoming quite prominent.

Jim