Hydraulic Oil

[Spiffy]

I know, espcially considering the improvements some have seen with synthetics, this has been discussed to death, but since I'm looking at straight hydraulic oil, thought maybe a new thread was warrented.

Anyway, my FIL (a tractor mechanic) was telling me that even on machines that recommend motor oil, the first thing they do is drop it out and run "hy-tran" (actually I think AG-Master is their brand). I guess mutli-viscosity, espcially detergent type, tends to foam in high pressure pumps, causing reduced power, higher temps, and shorter oil life.

I looked at the Ag-master stuff, and I'm pretty sure it's way too thin, but I saw some straight 40 non-detergent hydraulic oil at TSC, and got thinking it could be the answer. Now being single viscosity is that too heavy? Wrong altogether?

Side note, I have a leak to hunt down. Hope it's just a fitting I forgot to tighten, but we'll see. I noticed the advice in another thread to use soapy water and wash it out good first; looks like a good idea!

 

[KentT]

IMO, the straight 40 weight would be far to thick for trying to start the PT in your cold winters. Remember, the pumps are pumping all the time, even when you're just cranking the engine over....

I'm running 20W50 Amsoil and others are running 15W50 Mobil 1 -- and we all seem pleased with the change.

 

[J_J]

I am thinking of the same thing. I was told by a hydraulic tech that a single weight oil would work better in warm climates. The reason for the non-detergent is that if you do get water in the hydraulic tank or system, it will go to the bottom of the tank and stay there. Seems logical that non-detergent oil will not mix with water, therefore , no foaming.

Most people frown when I tell them that the hydraulic system uses regular motor oil.

No one seems to have a good answer why motor oil is used in the hydraulic system, after many thousands of hours have been used to determine what is the best hydraulic oil to use. Motor oil was not considered The idea that motor oil is cheap and can be found just about every where, just is not a good answer. I wonder if the manufacture of hydraulic equipment will warranty their systems if you use motor oil instead of the required hydraulic fluid.

I would suspect that motor oil is on the bottom of the list for use as a hydraulic fluid..

To fill a 20 gal tank of synthetic oil would cost around $200.00 To fill a 20 gal tank of motor oil would cost about $60.00 Who has the answer. If you do, let the rest of us know. I have been skeptical all along of motor oil in my system, but it does work. Does it work better than a good hydraulic fluid. I surely don't know. I have read most of the reports on the synthetics, and why they are the best, I am still not convicced. Why don't all manufacture of hydraulics equipment. specify the synthrtic product as the primary fluid, also, why are we having to guess wheather we will use synthetic motor, or synthetic hydraulic oil. Some of the synthetics are not 100% synthetic but they get away with calling them synthetic?

You all chime right in, I am sure you will.

It is still the owners choice.

 

[tracdoc]

Spiffy,

I agree with KentT that straight 40 Wt is probably too viscous for your apps, and would probably be brutal in Winter.

For a frame of reference, PT "recommends" 15W/40 motor oil for the hydraulics. (At least that's what the decal says on my machine). A 15W/40 corresponds to ~ISO68 viscosity when comparing with hydraulic oils.
A good reference comparison chart can be found {HERE}. If you will also look {HERE}, there is a helpful chart which shows the effect of temperature on different ISO grade hydraulic fluids. The reference temperature for the ISO grades is 40 deg C (~104 deg F), so one must be careful to look at the viscosity at the ranges one expects in their own hydraulics; 40 degrees is not a very "practical" reference temperature. In hot weather, our hydraulics may be in the 180+ degree range.

I discussed the possible changeover from motor oil to hydraulic oil with knowledgeable hydraulics folks, and ALL of them recommended using nothing less than an ISO68 hydraulic oil (our Winter temps are nowhere as cold as yours, so you may need to consider a lower ISO grade if you do a lot of winter work and do not have a heat source to keep your hydraulic oil above 20-25 degrees F.

I am planning to do the changeover when I reach ~150 hrs on the machine. I have dismissed Amsoil ATH as I consider it too thin at 5W/30 (ISO32). Right now, I have to admit that I am leaning to using a multi-grade Group IV synthetic motor oil for the change. I've not been able to sort out any special advantages of the straight ISO grade hydraulics (synthetic or not). The chemistry of the "additive packs" for these motor and hydraulic oils is mind boggling and that's where any performance (foaming, etc) and longevity differences will be seen. I have heard many times that the best performing hydraulic fluid is ATF precisely because of its superior additive pack. However, I 'm not quite ready to pop for 10 Gal of syn ATF. /forums/images/graemlins/grin.gif

J_J said: </font><font color="blue" class="small">( Some of the synthetics are not 100% synthetic but they get away with calling them synthetic?)</font>

What a can of worms that one is! The thorny issue of when is a non synthetic legally able to be called a synthetic has been discussed in the TBN lube forum from time to time. It dates back to about 1997-98 when Castrol stopped using polyalphaolefin (PAO) base stocks purchased from Mobil (the original basic component of "true" synthetic oil) in their Syntec oil. Castrol started to use much cheaper hydroprocessed petroleum base oils from Shell. Naturally, Mobil Oil complained to I believe something like the Council of Better Business Bureaus, which ruled in favor of Castrol, specifically allowing Syntec Motor Oil made from Shell ultra-high viscosity index petroleum oil to be labelled and sold as "synthetic."

To be fair, the manufacturers of PAO-based synthetics are not selling us a pure PAO product either. /forums/images/graemlins/blush.gif Somewhere in the fine print, manufacturers will point out that their oil is "fully synthetic, excluding carrier oils." The carrier oils are the oils in which the additive packs are dissolved. They constitute generally 10-20% of total product on a wt/wt basis. Bottom line is that even Group IV synthetics can have up to 20% dino oil in them. It's a rough world out there /forums/images/graemlins/confused.gif

It's quiet. Everyone in the house is asleep and I am afraid that I've run on too long....my apologies.

 

[Spiffy]

I had a few more questions about oil temps and pressures, so I spoke with Terry at PT today (I still give PT much credit for their friendly people). He said they use engine oil because it's the right viscosity, and any heavy duty engine oil would work fine (thus non-detergent engine oil might be an option). He also said they have little trouble with foaming; I wouldn't have noticed had the FIL not mentioned that, and of course the next day I noticed it does foam some.

Around here we have nasty temp swings which can draw moisture into the tank, so the non-det would make sense. However, maybe mulit-viscosity does make sense to combat the temperatures. If we never had it below 60F; I'd definitely look at straight 40 hydraulic fluid. Somehow seems to make sense to use oil formulated for 1000 to 5000psi; on the other hand maybe motor oils do handle PTs temps better.

Ironically, I remember IH touting hytran fluid that was supposed to be able to take on water without foaming (back in the 1980's); may have been a gimick though.

As a side note; I learned the fan setting is around 120F with 140 up to 160F normal running temps. Also, I always thought that the two high pressure ports were left and right (so I only checked left, the right being slightly less convienient under the linkage); but they are forward and backward.

I think I'll keep my options open, but look for a non-det in either an engine or hydraulic oil.

 

[Spiffy]

Great info tracdoc! Thanks for the charts too.

Ahhh yes, the synthetic/psuedo-synthetic debate; for hydrualics, I think I'll stay out of that one by sticking to dino motor oil vs. hydraulic oil; but can't argue reading about the many PT owners here that seem pleased with the synthetic.

I do think my final choice will be of the non-detergent type though. Also, I just looked it up; CNH still does have that hytran fluid; didn't check if the viscosity or temp range was compatiable.

 

[Spiffy]

A couple more good web pages:

Detergent in Hydraulics

Hydrualic Viscosity

Essentially, both articles say higher temp/viscosity range is the reason for motor oils. The first one quotes a mechanic saying that detergents should never go in hydrualics (for the same reasons I heard) but further states, if the viscosity range is needed it may not be entirely detrimental using modern detergent oils in modern pumps.

I'll need to do some looking at the AVH lubes, but may even stick with the same 15-40 (an advantage being no worry of doing a perfect flush). /forums/images/graemlins/crazy.gif

Oh it turns out that Hytran is a bit thin for me anyway, but stumbled across it's JD equivalent Hy-Gard which also cross-refs Super UDT - even if that is right (and I don't know it is), I don't think I'll be telling the orange guys /forums/images/graemlins/grin.gif

 

[weaver]

Yesterday I changed my Hyd oil in my 1430 with 400 hours. The old oil (10w40)had no foam in it, but the new 10w40 now has foam in it looks like foamy beer after I purged the system . The only reason I put 10w40 was it is under warrenty still. Is foam normal? Is water in the system? I called power trac and talked to Terry he said it would be fine ,I just would like another opinion. I also put a corked gasket on the top of the hydraulic tank with gasket seal the the one from the factory was hardly there I think it was #2 gasket sealer only. Thanks for any info

 

[Spiffy]

400hrs and still under warranty? Getting some seat time! /forums/images/graemlins/cool.gif

If it's really foamy, I wonder if you don't need to purge the main pump (charge pump port) a little better.

Else, you might have a little moisture, but from what I'm reading, nothing to loose sleep over. See if it settles overnight, and doesn't come back when you run it again.

It seems that nobody does stock the AWH (multi-grade hydraulic oil) around here; actually looks like synthetic is even more readily available. Unless in a warm enough climate to use single weight; perhaps 15W40 or synthetics are the best options.

I'm planning to stay with the 15W40 for now, but keep my eyes open for options.

 

[duane]

Just thought offer this up for comments.

From a post long ago, I could not find it, we talked about hydraulic oils in the PT. It went along these lines. (I still have most of the text since I would write my posts off-line and then copy/paste into the post text box. Charlie sent this in an e-mail to PT, but I'm not sure he heard back). Use of either a 10W-30 or 10W-40 viscosity oil, with a diesel API 'C'rating (Diesel engine oil), not necessarily the API 'S' (gas engine oil) rating. Whether it is synthetic or not, the API 'C' rating appears to be important. In Case skid steers, their hydraulic oil system is 10 gallons, similar to our PTs. They specify an API 'C' rated 10W-30 oil with one quart of Case HTO (hydrostatic oil transmission) additive per every 5 gallons. Apparently the Case HTO additive makes the diesel rated crankcase oil suitable for use in hydraulic systems.

Has anyone else heard of the Case HTO additive. I was contemplating on using Shell Rotella T 5w-40 with Case HTO additive when I do my change over. Would like more opinions though.

Duane