ATF Hygroscopic? Truck Tailgate Application.

[George7941]

I have always used Dex III ATF in tailgates. Last year I installed a new hydraulic power pack from Waltco and filled with Mobil Nuto 32 hydraulic fluid because Waltco recommended against ATF.

Waltco does not like ATF because it is hygroscopic. I would like to replace the hydraulic fluid with ATF because the 32 grade fluid does not perform well in very cold temperatures (below -20C). I replace tailgate fluids every two years.

Other tailgates (and power steering systems that call for ATF) have performed well for me with ATF. Shall I go ahead and replace the hydraulic fluid with ATF?

 

[Rand]

seems like that fluid is plenty thin but turns into jello about -20C
seems to have a very low Viscosity index
maybe a better hydraulic fluid?

For example the first syn. fluid I found with a data sheet.
https://www.amsoil.com/lit/databulletins/g2985.pdf
ISO 22
has a pour point of -49C
ISO 32 is -46C

I wouldn't use ATF.. but a syn hydraulic fluid.

 

[MolaKule]

If the spec if for an ISO 32 fluid, this would be my pick:

http://www.schaefferoil.com/documents/56-158-td.pdf

ATF is no more hygroscopic than hydraulic fluids.

 

[JHZR2]

Originally Posted By: Rand
seems like that fluid is plenty thin but turns into jello about -20C
seems to have a very low Viscosity index
maybe a better hydraulic fluid?

For example the first syn. fluid I found with a data sheet.
https://www.amsoil.com/lit/databulletins/g2985.pdf
ISO 22
has a pour point of -49C
ISO 32 is -46C

I wouldn't use ATF.. but a syn hydraulic fluid.


Why would something as benign as a hydraulic tailgate need a syn fluid??

 

[George7941]

Here is a bulletin from Waltco where they recommend hydraulic fluid over ATF because they claim ATF is hygroscopic

http://www.waltco.com/waltco/sitemgr.nsf/admin/htmlmedia/all/connection_020102/$file/020102_tech.htm

 

[George7941]

The link does not work but copy and paste will take you to the bulletin.

 

[Rand]

Originally Posted By: JHZR2


Why would something as benign as a hydraulic tailgate need a syn fluid??


a syn or something with a decent pour point.
The op's fluid pour point is awful.

That schaeffer's iso 32 looks fine too... but its a full syn.

The Op's intended use is Below -20C

The link the Op posted the recommended fluids all have decent Viscosity index.. His is near 100 which isnt recommended Example the one exxon fluid is 140+ with a pour point of -45c

for very low temp use a syn with even lower pour point would be ideal. or maybe 1 step down in viscosity.

 

[MolaKule]

Originally Posted By: George7941
Here is a bulletin from Waltco where they recommend hydraulic fluid over ATF because they claim ATF is hygroscopic

http://www.waltco.com/waltco/sitemgr.nsf/admin/htmlmedia/all/connection_020102/$file/020102_tech.htm


I disagree with that statement by Waltco.

Now dedicated hydraulic fluids DO have chemistry that mitigates the effects of increased moisture since many hydraulic systems have breathers that subjects the hydraulic fluid to atmospheric moisture.

 

[zeng]

Originally Posted By: George7941
I have always used Dex III ATF in tailgates. Last year I installed a new hydraulic power pack from Waltco and filled with Mobil Nuto 32 hydraulic fluid because Waltco recommended against ATF.
Waltco does not like ATF because it is hygroscopic. I would like to replace the hydraulic fluid with ATF because the 32 grade fluid does not perform well in very cold temperatures (below -20C). I replace tailgate fluids every two years.
Other tailgates (and power steering systems that call for ATF) have performed well for me with ATF. Shall I go ahead and replace the hydraulic fluid with ATF?

No.
Waltco is right.
You should avoid ATF if you can,go with a HVI High Viscosity Index Anti-wear hydraulic oil(shear-stable)designed for 5000 psi applications.

 

[GMorg]

The bulletin actually lists an ATF (DexII) as a recommendation.

 

[George7941]

Originally Posted By: GMorg
The bulletin actually lists an ATF (DexII) as a recommendation.

Yeah, I saw that. They recommend Dex II but not Dex III?

After careful consideration of all the replies to my query, I have concluded that what I need is a better quality hydraulic fluid.

I went with Nuto 32 because I had that in stock. Our local Toyota forklift dealer uses it for forklift hydraulics and so that is what I have been using in our Toyota forklift. Never thought to look into its specs but I now see it is not a premium oil.

My Mobil dealer has Univis N32 for $72 for a 5 gal pail, which is a good price for a premium oil. It has a pour point of -48C. We only get a few days in the winter when it drops below -20C, so the -48C should be adequate.

Here is the PDS for Univis
http://pds.mobil.com/Canada-English/Lubes/PDS/IOCAENINDMOUNIVIS_N-C_Series.aspx

I will switch over our other tailgates and our forklift to the Univis when it comes time for fluid replacement.

 

[MolaKule]

Originally Posted By: GMorg
The bulletin actually lists an ATF (DexII) as a recommendation.


Originally Posted By: zeng
Waltco is right.


So Waltco doesn't like ATF but recommends DexII ATF?

Forgive me if that sounds contradictory and non-sensical.

 

[zeng]

Originally Posted By: MolaKule
Originally Posted By: GMorg
The bulletin actually lists an ATF (DexII) as a recommendation.


Originally Posted By: zeng
Waltco is right.


So Waltco doesn't like ATF but recommends DexII ATF?

Forgive me if that sounds contradictory and non-sensical.

You should address this to the expert that says it, who manufactures and knows the product behaviour way,way better than you and me combined!
I don't quite see it as a contradiction, btw.
Think oils shear-stabililty property.

 

[Shannow]

Hydraulic oils in my industry experience tend to be better at bombing water out of suspension/emulsion. Crack the drain cock, and you will get free water, a small emulsion, and then clear fluid.

ATFs tend to have less clear water, more red milkshake, and a much less well defined barrier between the two fluids.

 

[MolaKule]

Originally Posted By: zeng
Originally Posted By: MolaKule
Originally Posted By: GMorg
The bulletin actually lists an ATF (DexII) as a recommendation.


Originally Posted By: zeng
Waltco is right.


So Waltco doesn't like ATF but recommends DexII ATF?

Forgive me if that sounds contradictory and non-sensical.

You should address this to the expert that says it, who manufactures and knows the product behaviour way,way better than you and me combined!
I don't quite see it as a contradiction, btw.
Think oils shear-stabililty property.
'


Just pointing out contradictory statements, but I think I know ATF's and Hydraulic fluids very well.

Quote:
Think oils shear-stabililty property.


Care to elaborate?