Engine Oil as Hydraulic Fluid??

[Jordon]

We had our mechanic out fixing a hydraulic hose the other day and he mentioned that some machines are starting to be outfitted with hydraulic systems that accept standard engine oil. Sounded like nonsense at the time, and it still does now. Is there anything to this?

 

[RonG]

Many machines including Caterpillar used engine oil in their hydraulic systems and also their transmissions.The D6 D was one example,there were many others.
The objective was to reduce the inventory of oils required to maintain your equipment.There may be a trend to do that again but it is not new by any means.Ron G

 

[John C.]

Engine oil is a whole lot more expensive than hydraulic fluid.

Around here in many cases hydraulic oil has to be biodegradable and have no heavy metals. That is something that engine oil will probably never be.

 

[willie59]

I was going to say same thing John C did, engine oil is sho nuff more expensive, and repeat what others have said as well, nothing new. Many old Komatsu machines spec'd engine oil in hyd system.

 

[RonG]

Back when I was running a Bantam C-366 with a leaky drive motor I was using three pails a day in it @ $25.00 a 5 gallon pail.
Dust control was a plus with that old girl.I took some pics of it the other day through the fence in the compound where she sits,the owner has gone out of business.I hate to see that go for scrap,it had a recently rebuilt 6V53 in it but cannot imagine anyone wanting to buy it unless it could be used for loading out of a stockpile or something because we had to break it down to move it.I have no idea what bulk engine oil would cost today.Ron G

 

[Komatsu 150]

My now old Komatsu specd Engine oil in the hydraulics. Besides reducing inventory like RonG said there is also the matter of people putting the wrong oil in the wrong places. I think this happens much more often than you would believe. I have to watch people constantly. For example: what we thought was an excellent car shop (not a quicky lube place) put 90 weight in my mothers 4WD transfer case (suppose to be Dexron ATF), truck shops are forever putting gear lube in Roadrangers, back when it was under warranty the Komatsu service manager left me urgent messages that the oil samples from our 150 came back with a warning: in the previous service someone put the wrong oil in the engine. He wasn't too thrilled when I reminded him they had done the previous service.

 

[biggrader]

RonG, just bought 2-2.5 gallon jugs of Mobil 1300 15w-40. $ 57.50 + tax, Also Mobil 424 hydraulic fluid in 55 gallon drum is $536.25. off-road diesel fuel is cheap though, only 3.90 per gallon.lol. ouch!! All oil products are costing an arm and leg now adays. doesnt leave any appendages to run equipment.

 

[RonG]

The time frame of that particular event was in the mid ninties.No doubt the prices have gone up a lot since then.This oil was the bargain brand from Acme Auto parts which was right around the corner.They delivered.Ron G

 

[CAT793]

Kind of depends on the Generation of Hydraulic System. A Variable Displacement Piston pump would barely last the week out on Multi Grade Engine Oil.

 

[MTI Mark]

The company that I work for (Mining Technologies International) uses 15w40 motor oil in the hydraulic systems of most of our mobile mining equipment with exception of our line of hydraulic jumbo drills. We use a load sensing hydraulic system (for fuel savings) via variable displacement piston pumps without any issues. I have contacted one of our engineers and will get an official answer as to why they spec motor oil vs hydraulic oil. I have spent several years working on mining equipment and I honestly dont believe it would make any difference whether you use motor oil or hydraulic oil. Oil filtration and cooling is the key to longevity of hydraulic components.
The engineer called back. Basically, it is a matter of preference. Either type of oil is fine for hydraulic system use. However, something worth noting for surface equipment: 15w40 motor oil has a "pouring point" of -30* C, whereas the Esso Nuto 32 hydraulic oil that we use has a "pouring point" of -36* C. Ambient temperature is generally not an issue for underground operations but may be a consideration if you are running your equipment in cold startup conditions up here in the northern zone. I would use whatever is more economical.

 

[Jordon]

Thanks for the responses everyone. I don't think we'll plan on using engine oil in our hydraulic system anytime soon, if ever. As a few of you pointed out, there's not much money to be saved anyway. I was just wondering.

Man, Atco responded to one of my posts. I feel honored!!!!

 

[MTI Mark]

My now old Komatsu specd Engine oil in the hydraulics. Besides reducing inventory like RonG said there is also the matter of people putting the wrong oil in the wrong places. I think this happens much more often than you would believe. I have to watch people constantly. For example: what we thought was an excellent car shop (not a quicky lube place) put 90 weight in my mothers 4WD transfer case (suppose to be Dexron ATF), truck shops are forever putting gear lube in Roadrangers, back when it was under warranty the Komatsu service manager left me urgent messages that the oil samples from our 150 came back with a warning: in the previous service someone put the wrong oil in the engine. He wasn't too thrilled when I reminded him they had done the previous service.

Komatsu 150, you are exactly right about about people putting the wrong oil in the wrong places. I got a report of one of our new loaders suddenly started smoking . Cummins came up and checked it out, replaced injectors. It was slowly clearing up. We later found out that a newbie had topped off the fuel tank with hydraulic oil. The sad part was there is a steel "FUEL" sign in 4" letters welded on to the fuel tank next to the filler.

 

[coalrulz]

About ten years, or more ago, Deere started to recommend changing out the hydraulic oil in 690E's with 15-40 or 10-30 engine oil. One of the stated reasons was because water seperates better from engine oil than hydraulic oil, most of us have seen this in action, hydraulic oil gets milky with oil in it while most engine oils do not. The 690E's used Linde hydraulic pumps and this was supposed to help with longevity. Most variable displacement axial piston pumps and motors have valve plates that etch when coming into contact with water.

 

[cutting edge]

Kind of depends on the Generation of Hydraulic System. A Variable Displacement Piston pump would barely last the week out on Multi Grade Engine Oil.

Couldn't be further from the truth.

Check into newer Deere Backhoes,Loaders,Bunchers,Skidders.....heck,the only deere machines that still use hydraulic oil,that i can think of,are the excavators.

 

[CAT793]

Couldn't be further from the truth.

Check into newer Deere Backhoes,Loaders,Bunchers,Skidders.....heck,the only deere machines that still use hydraulic oil,that i can think of,are the excavators.

If you sincerly believe that is the case why do we have Engine Oil,Hydraulic Oil and Gear Oil.......and not just Oil?

Hydraulic Oils have Friction Modifiers for very small clearances inside Pumps and Add Packs with Elements to keep the Oil Film Stable at Temperature.

Engine Oil has High Detergents to prevent Sludge Build Up, Dispersants to suspend Soot in the Oil and Add Pack's of elements that woud be Foreign/Unnecessary in a Hydraulic Circuit.

Your Argument is not Scientific. You have meerly found an example of a Manufacturer who has engineered their Product to be Durable/Versatile for the benefit/ease of their Customers/Operators.

I dont expect you to put much much value on my opinion but in my work environment we stopped using single Oil in multiple Compartments 20 Years ago. If you put Hydraulic Oil in the Hydralic Compartment (Wet Brakes) on a Large Mining Machine (Read CAT 793) it is un-drivable. They will Shudder/De-Laminate. Oil types have a very specific purpose and just because you have gotten away with it and it works does not make it right. What if running the correct oil allowed the Component to live 40% longer and cost 30% less to Overhaul???

 

[Scrub Puller]

Yair...As well as I remember Cat. specified thirty weight series three in all compartments of a D9g...even in the finals.

 

[MTI Mark]

CAT793, you bring up some good points about oil designed for specific applications... very valid. I think in this particular case engine probably possesses all the requierements that hydraulic oils do, but not the reverse. I dont think I would put hydraulic oil in my engine. I do know that MTI has used engine oil in their hydraulics for a long time and has seen no ill side effects from it. We have seen no issues with wet disc brakes (Dana axles), but that is an interesting point. I guess the bottom line is, use what the OEM specifies and you should be good.
Are you involved in surface or underground mining? What do you do?

 

[RocksnRoses]

The specification for our 1991 Liebherr L541 wheel loader is 15w/40 engine oil in the hydraulics, which also feeds the hydrostatic drive variable displacement piston pump and hydraulic motor on the transmission. A quick look at both Mobil and Valvoline recommendations for all Liebherr equipment today, is engine oil in the hydraulics from their wheel loaders right through to their R996 excavator which has a capacity of up to 6,000 litres.

RnR.

 

[Komatsu 150]

Using what the OEM recommends is the proper thing to do. The point here is a great many companies specify engine oil in hydraulics. Designed for it and work perfectly fine. Just to make it interesting I've also seen quite a few instances where a component made by one supplier will be used in various brands of equipment and the equipment manufacturers will specify different oils. They have their reasons so we do what they say. A perfect example is steering systems in trucks. Hydraulic oil, power steering fluid, Dexron ATF, all in the exact same steering box and pump.

 

[akroadrunner]

My Volvo Loader takes motor oil in the hydraulic tank, and transmission. Specified in the manual.