[Nitebird]

What type of fluid should be used in a 1979 Trans Am power steering pump?

[78w72]

Dexron 3 or newer backward compatible like valvoline maxlife that is fully synthetic.

[JLBIII]

I'm running Lucas power steering fluid in mine. Always had good results with Lucas products.

[Nitebird]

Originally Posted by JLBIII

I'm running Lucas power steering fluid in mine. Always had good results with Lucas products.

Does it say that it is the equal to Dextron Mercon lll

[Nitebird]

Originally Posted by 78w72

Dexron 3 or newer backward compatible like valvoline maxlife that is fully synthetic.

Thanks for the reply!

[Schurkey]

Originally Posted by Nitebird

What type of fluid should be used in a 1979 Trans Am power steering pump?

What does it say on the fill cap? Use that, or the modern equivalent.

BEWARE of "backwards-compatible" transmission fluid that may be backwards-compatible IN AN AUTOMATIC TRANSMISSION, but is not authorized for non-transmission uses such as manual transmissions, transfer cases, etc.

[78w72]

Originally Posted by Schurkey

BEWARE of "backwards-compatible" transmission fluid that may be backwards-compatible IN AN AUTOMATIC TRANSMISSION, but is not authorized for non-transmission uses such as manual transmissions, transfer cases, etc.

Can you elaborate on this? or show some type of documentation that a modern trans fluid rated for dex 3 use cant be used in a non trans item like power steering or transfer cases? Never seen that stated on any modern dex 3 compatible fluids or from manufacturers of vehicles. Just curious how one is supposed to know what can/cant be used in which vehicles.

I have had excellent results using maxlife & even supertechs modern dex 3 compatible/rated fluids in old power steering units as well as modern p/s with rack & pinion & transfer cases in 4x4 vehicles.

[1968GTO421]

Originally Posted by 78w72

Dexron 3 or newer backward compatible like valvoline maxlife that is fully synthetic.

I came across this when googling Valvoline Maxlife:

https://valvolinechemicals.com/produ...ing-fluid-32oz

FWIW

[Schurkey]

Originally Posted by 78w72

Can you elaborate on this? or show some type of documentation that a modern trans fluid rated for dex 3 use cant be used in a non trans item like power steering or transfer cases? Never seen that stated on any modern dex 3 compatible fluids or from manufacturers of vehicles. Just curious how one is supposed to know what can/cant be used in which vehicles.

From GM's service bulletin
http://ww2.justanswer.com/uploads/he..._Dexron_VI.pdf
#04-07-30-037D: Release of DEXRON-VI Automatic
Transmission Fluid (ATF) - (Nov 21, 2007)

DEXRON®-VI can be used in any proportion in past model vehicles equipped with an automatic transmission/transaxle in place of DEXRON®-III (i.e. topping off the fluid in the event of a repair or fluid change). DEXRON®-VI is also compatible with any former version of DEXRON® for use in automatic transmissions/transaxles.

It is, therefore, compatible with Dex III, in an automatic transmission. But also:

The content of this bulletin does not apply to manual transmissions or transfer cases. Any vehicle that previously required DEXRON®-III for a manual transmission or transfer case should now use P/N 88861800. This fluid is labeled Manual Transmission and Transfer Case Fluid. Power Steering Systems should now use P/N 9985010 labeled Power Steering Fluid.

So, as an example, Dex VI is backwards-compatible in auto transmissions using any version of Dexron, but NOT suitable for manual transmissions, transfer cases, and PS systems.

Note that this bulletin may or may not have been superceded by a newer version than the "D" quoted here, and that newer version may or may not have different information regarding Dex VI useage (but probably not, since GM is still selling pretty blue Auto-Trac transfer case fluid that looks like the old B&M Trick Shift, and they're still selling power steering fluid.)

I still want to know what his fill-cap specifies for fluid use. And--I guess--if it specifies Dexron, then buying "Dex-Merc", supposedly the exact formula as the old Dexron III H, but without the Dexron trade name is probably OK. I'm not going to use ATF in a PS system. When I need PS fluid, I buy PS fluid. On my Trailblazer, I buy GM Cold Climate PS fluid, because it whines like a three-year-old with "regular" GM PS fluid three seasons of the year.

[JLBIII]

Originally Posted by Nitebird

Does it say that it is the equal to Dextron Mercon lll

It reads " Formulated for use in GM, Ford , Chrysler, Toyota. Not for use in Honda or Acura vehicles"

[Tim Corcoran]

GM recommended using Dextron ATF for the power steering system in these older Pontiacs. I would follow the manufactures recommendation.

[Schurkey]

Originally Posted by Nitebird

Dextron Mercon lll

Originally Posted by Tim Corcoran

Dextron ATF

There is no "t" in Dexron.

Dex-Merc "Dexron III equivalent" is probably suitable. Dexron VI is not. I'm fairly sure the newer Dexron formulas--HD and ULV--are also not suitable.

Every parts store in America sells "Power Steering Fluid" advertised for GM systems.

[78w72]

Thanks for the service bulletins, but VI (6) is a lot newer fluid than what I was saying for dex3 compatible to use on p/s or transfer cases. the bulletin seems more about warranty use or for topping off & explains not to use it in transfer cases, manual trans & p/s systems that state dex3... VI doesnt really meet the true backward compatible definition in that case.

Just to clarify, when i said "backward compatible" i meant other fluids that are not VI, such as maxlife, valvoline dex/merc, supertech ATF or other brands rated for dex2/3 use. most all of these fluids specifically say not to be used in any vehicle that requires VI fluid but they are all rated for dex2/3 use in any system.

For a 1979 trans am, the p/s says to use dex3, many other vehicles use dex3 as well, i have a 2009 toyota 4runner, toyota is very specific about what ATF to use in their transmissions for 2005 & later, toyota WS, maxlife ATF is rated for use with WS so lots of guys including me do a full exchange with maxlife with excellent results... however, the p/s system says to use dex3... not universal power steering fluid.

I choose to use what the manufacturer says to use, a true backward compatible fluid for dex2/3 use, like those i mentioned, not VI.

[Sirrotica]

Every parts store in America sells "Power Steering Fluid" advertised for GM systems.

That statement is very true, a pure hydraulic system has no need for fluids with friction modifiers. It needs to be the correct viscosity, and function as a hydraulic oil.

Years of working in GM dealer service departments we used the cans/bottles labeled "GM Power Steering Fluid" to top off, or refill the cars power steering fluid. GM dealers have a specific fluid that works just fine, and is less prone to aerating. It's easier to get the air out of a system that has power steering fluid in it, than one filled with Dexron ATF after working on it. That's from real world experience of using both fluids.

GM did say that topping off a system with dexron is allowable in certain systems designed for it. In almost every case at a GM dealer, we used power steering fluid over dexron, this was in the mid 70s, to early 80s that I was working in a chevy, and a buick dealership, covering the time frame the OP asked about, 1979. I always still try to use the correct spec power steering fluid.

As has been mentioned in reference to Honda, and Acura systems, I also worked in a Honda dealer for about a year in the mid 80s. Substituting ATF in on of those systems will cost you dearly in failed parts. Honda cars have no tolerance of using the wrong fluids in their systems.

In the late 80s I also started working on aerial lift manlifts, whch are run basically on 100% hydraulic systems. Of all the manufacturers that I worked on, only one specified dexron for their hydraulic systems, the rest all went with specific hydraulic fluids for hydraulic systems.

So while dexron will work in a hydraulic system, it may not be the best choice for a system that needs no friction modifiers for wet clutches. In all the GM service departments I've worked at, the parts department supplied you with power steering fluid for steering repairs, not derxron. As Shurkey has mentioned, correct GM spec power steering fluid is widely available in the US. There is no downside to using it in a GM system.

[Don 79 TA]

i tried a synthetic PS fluid and i had leaks at the bottom of the steering box. I'm sure its age related as i've never touched it.
I flushed it out and put in prestone steering fluid and no issues with leak, or system use.

[78w72]

I looked at the cap on my 81 t/a & it says "use approved fluid"... checking the owners manual it definitely says to use "power steering fluid" with a part# that im sure is obsolete now...

With that being said, I was wrong saying that dex3 is the specified fluid for this era of GM power steering systems, however, dex 3 is acceptable to use as mentioned above & wont cause any damage, ive been using it or other more modern ATFs mentioned for 20-25+ years with no issues. If i ever decide to change it out I would probably go with the maxlife p/s fluid posted above.

[burd]

I use Dextron trans fluid in my car

[Formulas]

i use the clear generic power steering fluid since i cant remember when
Valvoline is the gallon jug that i have
And to tell the truth i think i even used it in my old 2007 Honda when i flushed out the system

Never had a problem going to put in my 1977 C20 longbed that iam building the engine for now

[Cliff R]

That statement is very true, a pure hydraulic system has no need for fluids with friction modifiers. It needs to be the correct viscosity, and function as a hydraulic oil.

+2

WAY back in the day I used Dextron III in all the power steering pumps on my GM vehicles. At some point in the late 1970's or early 1980's (bad cases of CRS going on here) I read or heard someplace NOT to run ATF in power steering systems as it contains friction modifiers.

Up to that time never had a single issue and had been dumping Dextron III into anything I'd owned with power steering with zero issues anyplace. Even so I switched over to using plain old clear hydraulic oil in power steering systems and continue that practice to this day..........

[Cliff R]

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