PS Fluid vs Dextron III

[dirtydannyd]

Have a power steering unit that specifies Dexron 3. For a few bucks more you can get Power Steering fluid that seems to be Dexron 3. Like Castrol has both Dexron 3 and ps fluid. Is there really a difference or is the ps fluid just a markup Dexron 3?
Cheers.

 

[Bgallagher]

use what it is specified for. Castrol Dex 3 is good stuff.

 

[901Memphis]

The PS fluid is usually less robust than ATF, although they seem to run fine on either they don't need a ton of additives for the system.

I've always converted my stuff from PS fluid to synthetic ATF. My Buick specifies GM power steering fluid but works fine with Maxlife

 

[4D-56]

Use at least the Dex 3 stuff. Where possible, I switch vehicles over to Amsoil ATF, its a great hydraulic fluid. Experience of changing a PITA steering rack stays with you!...."how can I make this st. rack last a looong time..?" lol

 

[RooflessVW]

Get some Dex VI! It is better in every measurable way, and designed to be suitable in ALL Dex III applications!

 

[Ramblejam]

Originally Posted By: rooflessVW
It is better in every measurable way

Bold statement. Since this is a PSF vs. ATF thread, why don't you talk to us about ZDDP...

 

[RooflessVW]

Originally Posted By: Ramblejam
Originally Posted By: rooflessVW
It is better in every measurable way

Bold statement. Since this is a PSF vs. ATF thread, why don't you talk to us about ZDDP...


What? Dex VI is the successor to Dex III... GM designed Dex VI to be suitable in ALL Dex III applications, not me.

What does that have to do with ZDDP? Especially in a power steering system.

 

[DWC28]

What is critical for a power steering fluid?
Long life – same as for an ATF
Viscosity stability – same as for an ATF
Cold flow –same as an ATF
Pump wear protection –same as for an ATF
Fuel economy –same as an ATF.
Seal and hose protection –same as an ATF.
Rust and corrosion protection – same as an ATF

Why is DEXRON VI better than DEXRON III?
Longer life
Better fuel economy
If those are not important to you DEXRON III is fine.
If you want a longer life DEXRON III use synthetic.

What is a characteristic of a cheap power steering fluid?
No VII. –Same as industrial hydraulic fluid.

 

[Ramblejam]

Originally Posted By: rooflessVW
What? Dex VI is the successor to Dex III... GM designed Dex VI to be suitable in ALL Dex III applications, not me.

Your argument is...

Dex III was factory fill. Dex VI supersedes Dex III. Therefore, Dex VI is the best power steering fluid choice.

See any possible flaws in that line of reasoning?

Originally Posted By: DWC28
What is critical for a power steering fluid?

The same could be said of virtually any hydraulic system. Of course, once removed from the consumer/disposable space, we don't go around dumping ATF into every system, now do we?

ATF was chosen as PSF for the same reason it's also utilized as a manual transmission fluid; minimizes expenditure and simplifies production ops all while working well enough. Doesn't mean it's the best choice.

 

[DWC28]

Originally Posted By: DWC28
What is critical for a power steering fluid?

The same could be said of virtually any hydraulic system. Of course, once removed from the consumer/disposable space, we don't go around dumping ATF into every system, now do we?

ATF was chosen as PSF for the same reason it's also utilized as a manual transmission fluid; minimizes expenditure and simplifies production ops all while working well enough. Doesn't mean it's the best choice.

[/quote]

We disagree. Almost all of the time an ATF will be the best choice. However there is a lot of difference between ATFs.

 

[RooflessVW]

My line of reasoning is that Dex VI, with regards to a system designed for Dex III, is:

Dex VI is more shear stable. Lower starting viscosity and higher minimum viscosity in use.
It is made from superior base stocks
It has a superior ad pack
It's still cheap.

You still have not replied to my question... Why did you bring up ZDDP? Why would that particular "holy grail" additive be relevant to this topic of discussion, or indeed, to any power steering system.?

 

[Ramblejam]

Originally Posted By: rooflessVW
with regards to a system designed for Dex III

Who said it was designed for Dex III?

As for ZDDP -- it was mentioned as to get the opinion from you, who declared a fluid "better in every measurable way", on the differences in additive packages between common Dex VI ATF and commercial/industrial hydraulic oils.

 

[RooflessVW]

The very first sentence from the OP is: "Have a power steering unit that specifies Dexron 3."

 

[Ramblejam]

Which is completely different than designed for; don't conflate the two.

 

[RooflessVW]

Originally Posted By: Ramblejam
Which is completely different than designed for; don't conflate the two.


Alright, fine. I'm done having this stupid [censored] conversation.

His car specifies Dex III, I recommended Dex VI, as it is superior to Dex III.

I'm not sure what you're digging at or why, and I don't care.

 

[Ducman]

Originally Posted By: dirtydannyd
Have a power steering unit that specifies Dexron 3. For a few bucks more you can get Power Steering fluid that seems to be Dexron 3. Like Castrol has both Dexron 3 and ps fluid. Is there really a difference or is the ps fluid just a markup Dexron 3?
Cheers.


I think it's the exact same stuff.
The only difference is the quantity it's packaged in, with the PSF typically being in a smaller container for the primary purposes of top ups. The cost will naturally be higher due to the smaller quantity.

 

[Ducman]

Originally Posted By: rooflessVW
Originally Posted By: Ramblejam
Which is completely different than designed for; don't conflate the two.


Alright, fine. I'm done having this stupid [censored] conversation.

His car specifies Dex III, I recommended Dex VI, as it is superior to Dex III.

I'm not sure what you're digging at or why, and I don't care.


Your reasoning is fair taking into consideration the Dex VI fluid was initially intended to supersede Dex III in all applications.
In the fullness of time the wisdom of this advertised feature was found to be flawed in terms of manual transmissions, as the fluid is primarily required to ensure longevity with Dex VI being incapable of performing this function in any way.

The OP's question relates to a power steering fluid application and primarily between DEX III and power steering fluid fluid.
There is one major flaw with Dex VI, and that is the cost.
It's simply too expensive for use in a power steering fluid application where the system was designed around Dex III and primarily functions as an hydraulic fluid.

Taking into consideration the cost, I think DEX VI is not a contender unless it's capable of providing some tangible fuel economy benefits, or perhaps an improvement in steering feel/feedback.