Let's revisit the oil vs. hydraulic question???

[sterlclan]

The origional question was switching to "motor oil". My manual from the company, not the dealer says to use "Bobcat Hydrostatic Fluid" or something of the sort and gives a part number. It goes on to say if you cannot get it use 10W-30.
I agree that modern motor oils have much more detergent than they used to and may not be the best option in a hydraulic system. If you read on a jug of Bobcat brand fluid, they have adsolutley no specs on there. However, I seriously doube that part of their corporate structure that has helped them grow for 50 years has been to plan for failure. It seems to me, that they use innovation as a selling tool rather than saying, your last one broke, so you need a new one. I would assume that Bobcat used some engineers when they designed their equipment and maintenance recommendations as well.

sae 30 non detergent motor oil? Jeff

 

[OldMachinist]

OldMachinist
By my previous post It looks like I missed the point you were about the manufacturer getting the machine past the point of liability before things starting failing. My point was more about built in self destruction.As a part time bodyman in the 70s and 80s I have to think they knew how long it would take for rust thru.I have an old N/H lx865. The pumps sound fair for about 3500 hours. I think when the pump start whinning Ill probably go with more viscosity with my oil. Do you think that might extend life a little or would that be a mistake. Mike

mullud,
Hydraulic oils have viscocity ratings like engine oils. So if your original oil was say ISO-32 then it would be like 5 to10wt engine oil. Increasing the viscosity might have some side effects like longer warm-ups and decreased lubrication when cold and make pumps work harder and fail sooner. But like someone said here Bocat and other machine builders don't tell us what rating their branded oil is so how can we know what viscosity they are. I use the Bobcat oil in my 453 but in my old farm tractors I use ISO grades 46 and 68 it depends on what season they will see more use.

 

[Tazza]

mullud,
Hydraulic oils have viscocity ratings like engine oils. So if your original oil was say ISO-32 then it would be like 5 to10wt engine oil. Increasing the viscosity might have some side effects like longer warm-ups and decreased lubrication when cold and make pumps work harder and fail sooner. But like someone said here Bocat and other machine builders don't tell us what rating their branded oil is so how can we know what viscosity they are. I use the Bobcat oil in my 453 but in my old farm tractors I use ISO grades 46 and 68 it depends on what season they will see more use.

I can't remember who it was, but i was told that Bobcat branded oil was essentially what they could get their hands on cheap. They didn't stick to one brand but no doubt they would have a set grade that they would use. This info was from someone that worked as a mechanic for Bobcat too.
jklingel - I was replying to OldMachinist's post about the oil pressure ratings, i had no idea oils were made for different pressures. I knew about detergents but thats about it. As for compressing oil i was just saying you can compress a liquid more or less indefinitely but there is no advantage, it doesn't get smaller, unlike gasses.

 

[OldMachinist]

I can't remember who it was, but i was told that Bobcat branded oil was essentially what they could get their hands on cheap. They didn't stick to one brand but no doubt they would have a set grade that they would use. This info was from someone that worked as a mechanic for Bobcat too.
jklingel - I was replying to OldMachinist's post about the oil pressure ratings, i had no idea oils were made for different pressures. I knew about detergents but thats about it. As for compressing oil i was just saying you can compress a liquid more or less indefinitely but there is no advantage, it doesn't get smaller, unlike gasses.

Tazza I read somewhere that the molecules of oils do change shape under pressure and that hydraulic oils are designed to keep the shape spherical under pressure instead of flattening out. I just tried to find that info again and can't. I'll keep looking for it.
Another note on changing viscosity is that the system pressures will increase as viscosity does so if you change oils you may have to adjust your relief valve.

 

[TriHonu]

Tazza I read somewhere that the molecules of oils do change shape under pressure and that hydraulic oils are designed to keep the shape spherical under pressure instead of flattening out. I just tried to find that info again and can't. I'll keep looking for it.
Another note on changing viscosity is that the system pressures will increase as viscosity does so if you change oils you may have to adjust your relief valve.

The science of oil technology is probably far more complex than any of us wants to take the time to study. All petroleum based oils are produced from crude oil that has been refined into specific oils with additives added to optimize its performance for specific applications.
My manual on Industrial Fluid Power makes the following points:
1. Ordinary high quality motor oil is not recommended for general hydraulic use because it does not have some of the characteristics which are desirable in hydraulic applications. It is often used in simple systems due to its cost compared to the cost of the equipment.
2. Hydraulic oils are manufactured with a specific viscosity to provide adequate flow that not only powers the circuit but also lubricates the system components. It also has additives that control the Viscosity Index (VI). The VI is the range of viscosity change as the temperature of the oil changes. There are numerous additives for Anti-Foaming, Oxidation Resistance, Rust Inhibitors and Demulsifying Agents that help separate any water that enters the system from the oil. All these factors and many more are considered when the primary function of hydraulic oil is power transmission, not lubrication.
Bobcat recommends hydraulic fluid changes at 1000 hours or when the system has been opened for repair or when you identify the oil is contaminated. So for most of our equipment you may have changed the oil once or twice in you loader. Considering there is no procedure identified by Bobcat to totally drain the system, only the reservoir, we are really only talking about 10-12 gallons at most. The last 2.5 gallon jug of Hydraulic oil cost me $22.30 and the hydraulic filter was $33.78 so rounding up less than $100 for the fluid change. Considering the cost to purchase the loader and the cost per hour to operate this is not a high dollar preventive maintenance item. However the cost to repair failed hydraulic/hydrostatic components will empty a wallet in a hurry.

It does not make sense to me to try to save a couple of dollars by using motor oil in the hydraulics.
Yes motor oil will allow the hydraulics to function. My neighbor uses non detergent motor oil in his hydraulics. He buys it in bulk and runs it in all his equipment and has not had any problems. However he does not run/own any hydraulic attachments. I on the other hand do run a snow blower, soil preparer and backhoe that put a significant and sustained load on my hydraulics on top of the normal loads.
Contamination of the oil is the enemy and you hydrostatic drive is much more sensitive to contamination than the rest of the system. I change my filters and oils much more frequently than the manual recommends. To me it is cheap insurance

One of the trade magazines ran an article not too long ago about particulate contamination in hydraulic systems. There are a number of companies now making filtering machines that will pull hydraulic fluid out of your reservoir tank and filter it and return it to the system while you machine sits at idle. Some of the big contractors are using this technology to significantly extend the life of their larger equipment. These high performance filters will filter out much more than the installed factory filters.

 

[jklingel]

The science of oil technology is probably far more complex than any of us wants to take the time to study. All petroleum based oils are produced from crude oil that has been refined into specific oils with additives added to optimize its performance for specific applications.
My manual on Industrial Fluid Power makes the following points:
1. Ordinary high quality motor oil is not recommended for general hydraulic use because it does not have some of the characteristics which are desirable in hydraulic applications. It is often used in simple systems due to its cost compared to the cost of the equipment.
2. Hydraulic oils are manufactured with a specific viscosity to provide adequate flow that not only powers the circuit but also lubricates the system components. It also has additives that control the Viscosity Index (VI). The VI is the range of viscosity change as the temperature of the oil changes. There are numerous additives for Anti-Foaming, Oxidation Resistance, Rust Inhibitors and Demulsifying Agents that help separate any water that enters the system from the oil. All these factors and many more are considered when the primary function of hydraulic oil is power transmission, not lubrication.
Bobcat recommends hydraulic fluid changes at 1000 hours or when the system has been opened for repair or when you identify the oil is contaminated. So for most of our equipment you may have changed the oil once or twice in you loader. Considering there is no procedure identified by Bobcat to totally drain the system, only the reservoir, we are really only talking about 10-12 gallons at most. The last 2.5 gallon jug of Hydraulic oil cost me $22.30 and the hydraulic filter was $33.78 so rounding up less than $100 for the fluid change. Considering the cost to purchase the loader and the cost per hour to operate this is not a high dollar preventive maintenance item. However the cost to repair failed hydraulic/hydrostatic components will empty a wallet in a hurry. It does not make sense to me to try to save a couple of dollars by using motor oil in the hydraulics.
Yes motor oil will allow the hydraulics to function. My neighbor uses non detergent motor oil in his hydraulics. He buys it in bulk and runs it in all his equipment and has not had any problems. However he does not run/own any hydraulic attachments. I on the other hand do run a snow blower, soil preparer and backhoe that put a significant and sustained load on my hydraulics on top of the normal loads.
Contamination of the oil is the enemy and you hydrostatic drive is much more sensitive to contamination than the rest of the system. I change my filters and oils much more frequently than the manual recommends. To me it is cheap insurance
One of the trade magazines ran an article not too long ago about particulate contamination in hydraulic systems. There are a number of companies now making filtering machines that will pull hydraulic fluid out of your reservoir tank and filter it and return it to the system while you machine sits at idle. Some of the big contractors are using this technology to significantly extend the life of their larger equipment. These high performance filters will filter out much more than the installed factory filters.

Tazza: "As for compressing oil i was just saying you can compress a liquid more or less indefinitely but there is no advantage, it doesn't get smaller, unlike gasses." Ahhh sooo. NOW I get what you were saying. Thanks for clarifying. TriHonu: Wow. There is a brain full. Thanks. I think I'll stick w/ hydraulic fluid. Sleep is important. For me, case closed.

 

[tsanders]

Tazza: "As for compressing oil i was just saying you can compress a liquid more or less indefinitely but there is no advantage, it doesn't get smaller, unlike gasses." Ahhh sooo. NOW I get what you were saying. Thanks for clarifying. TriHonu: Wow. There is a brain full. Thanks. I think I'll stick w/ hydraulic fluid. Sleep is important. For me, case closed.

when i was in the excavating buisness i found out real quick that hoses and cylinders will not last long if you dont run hyd oil with R@O. i kept a 632 bobcat that i run 30 weight engine oil in but i have to buy the cheapest oil i can find to keep from getting a detergent oil. i usually have to purchase at dollar general to get non detergent. this will probably be impossible to get before long and i will then switch to hyd oil. will that then solve the oil vs. hyd problem? lol

 

[Tazza]

when i was in the excavating buisness i found out real quick that hoses and cylinders will not last long if you dont run hyd oil with R@O. i kept a 632 bobcat that i run 30 weight engine oil in but i have to buy the cheapest oil i can find to keep from getting a detergent oil. i usually have to purchase at dollar general to get non detergent. this will probably be impossible to get before long and i will then switch to hyd oil. will that then solve the oil vs. hyd problem? lol

All good food for thought. With the 751 i am SLOWLY working on i need to work out just what oil i'm going to run. I want to make sure i don;t kill the poor thing just when i get it going again. My dad was talking to some people and they said their listings showed to use 10 grade oil, i'm assuming its a grade of hyd oil. Few more phone calls are needed i think.

 

[Fishfiles]

All good food for thought. With the 751 i am SLOWLY working on i need to work out just what oil i'm going to run. I want to make sure i don;t kill the poor thing just when i get it going again. My dad was talking to some people and they said their listings showed to use 10 grade oil, i'm assuming its a grade of hyd oil. Few more phone calls are needed i think.

Long before I read Bobcat's service bulletin which makes the recomendation to switch to hydraulic oil in the hyd. system in place of the formerly used motor oil , I was using hydraulic oil , I have said my feelings on other threads on this topic so I won't go there -------the real debate should be on what type and weight of hydraulic oil should be used to substitue the OEM recomended hydraulic fluid that Bobcdat sells , a MSDS sheet taken to your local oil distributor would give you the answer , hydraulic oil comes in so many variations , 10 weight , 32, 68 with many different additives such as anti foaming , non electrical conductive to name a few , different systems have different needs , personally I feel HyGuard HG fluid is the best all around hydraulic oil out there , it's alittle more expensive and thicker

 

[tsanders]

Long before I read Bobcat's service bulletin which makes the recomendation to switch to hydraulic oil in the hyd. system in place of the formerly used motor oil , I was using hydraulic oil , I have said my feelings on other threads on this topic so I won't go there -------the real debate should be on what type and weight of hydraulic oil should be used to substitue the OEM recomended hydraulic fluid that Bobcdat sells , a MSDS sheet taken to your local oil distributor would give you the answer , hydraulic oil comes in so many variations , 10 weight , 32, 68 with many different additives such as anti foaming , non electrical conductive to name a few , different systems have different needs , personally I feel HyGuard HG fluid is the best all around hydraulic oil out there , it's alittle more expensive and thicker

fishfiles did this bulletin include all models and years. if so you would think bobcat would give you info on what type to use because as you point out there are so many types that a lot of oil distributors dont even stock all of them. my brother runs a terramite and he had to drive 90 miles to get the right fluid for it. he checked with 4 distributers along the way. there surely has to be a way to find out what oil or hyd. to use in our machines

 

[OldMachinist]

fishfiles did this bulletin include all models and years. if so you would think bobcat would give you info on what type to use because as you point out there are so many types that a lot of oil distributors dont even stock all of them. my brother runs a terramite and he had to drive 90 miles to get the right fluid for it. he checked with 4 distributers along the way. there surely has to be a way to find out what oil or hyd. to use in our machines

fishfiles Can you get a copy of the bulletin and post an image of it for all to see.
Like it was stated before Bobcat doesn't publish what grade their branded oil is. But since they only have one grade that they sell we can assume that it's an all weather multi-grade oil. Very few oil manufacturers make a multi-grade hydraulic oil and most are branded by one of the farm equipment manufacturers, John Deere Hy-Gard, Kubota Super UDT and Amsoil Synthetic Tractor Hydraulic are the couple I found.
Using the wrong viscosity oil can lead to component failure. Too thin and it thins out at high temp and parts wear quickly. Too thick and pumps cavitate.

 

[TriHonu]

fishfiles Can you get a copy of the bulletin and post an image of it for all to see.
Like it was stated before Bobcat doesn't publish what grade their branded oil is. But since they only have one grade that they sell we can assume that it's an all weather multi-grade oil. Very few oil manufacturers make a multi-grade hydraulic oil and most are branded by one of the farm equipment manufacturers, John Deere Hy-Gard, Kubota Super UDT and Amsoil Synthetic Tractor Hydraulic are the couple I found.
Using the wrong viscosity oil can lead to component failure. Too thin and it thins out at high temp and parts wear quickly. Too thick and pumps cavitate.

You guys got me thinking. I figure the hydrostatic pump is the most expensive item in the system and should be the item with most specific requirements.
I got the number off the pump in my 763, It is a Sauer Danfoss M91-35916 CCW. I called Sauer's Customer Service Dept and they identified it as a Series 40. They directed me to the Sauer Danfoss website and told me to open the Hydrostatic Propel Products and then the Series 40 Axial Piston Pumps and Motors. There you can down load the Service Manual and Technical Information on the pump.
They also directed me to a Technical Information on Hydraulic Fluids and Lubricants publication that is available from the same site under:
Sauer-Danfoss then Systems/Applications Technical Information then Technical Information (TI) then Hydraulic Fluids and Lubricants TI_11-2007_RevGC.pdf
Page 21 states:

Sauer-Danfoss hydrostatic components may be operated with a variety of hydraulic fluids.
The rated data which we publish in our Technical Information and Service Manuals are based on the use of premium hydraulic fluids containing oxidation, rust, and foam inhibitors. These fluids must also possess good thermal and hydrolytic stability to prevent wear erosion, and corrosion of the internal components. For some applications good anti-wear additives are required.
[FONT=Myriad,Myriad]
The following hydraulic fluids are suitable[/FONT]
:

• Hydraulic Oil ISO 11 158 - HM (Seal compatibility and vane pump wear resistance per DIN 51 524-2 must be met)
• Hydraulic Oil ISO 11 158 - HV (Seal compatibility and vane pump wear resistance per DIN 51 524-3 must be met)
• Hydraulic Oil DIN 51 524-2- HLP
• Hydraulic Oil DIN 51 524-3 - HVLP
• Automatic Transmission Fluid ATF A Suffix A (GM)
• Automatic Transmission Fluid Dexron II (GM), which meets Allison C-3 and Caterpillar TO-2 test
• Automatic Transmission Fluid M2C33F and G (Ford)
• Engine oils API Classification SL, SJ (for gasoline engines) and CI-4, CH-4, CG-4, CF-4 and CF (for diesel engines)
• Super Tractor Oil Universal (STOU) special agricultural tractor fluid

There are also charts that detail the oils and the temperature ranges that are acceptable for those oils. I phoned their Technical Support Line to clarify a couple of points:
1. They first recommend Premium Hydraulic Fluids and told me Mobil DTE 15M is very good. I live in southern Minnesota and they recommended
ISO 46 for the temperatures we normally see 100 to 0 degrees F.
OR
ISO 32 if we were operating a lot in the -10 to -20 degrees F.
2. He stated while any of the acceptable oils listed above will work, choosing the appropriate viscosity for your climate is very important and keeping the oil clean is critical.
3. Mixing the mineral based oils is not a significant issue since totally draining the system is not cheap or easy. However he stated if you want to change to some of the exotic or biodegradable oils you can have some nasty results if the system is not totally drained and flushed as some of these oils are incompatible with the mineral based hydraulic fluids.
4. If you choose to use the acceptable API Engine Oils and Automatic Transmission Fluids be aware that the oils have a high shear-ability which results in the oil performing at a much thinner viscosity under high loads. For example SAE 10W oil under high load will perform like an SAE 6W under high load. Too thin and you can start having parts rubbing together.
5. Using a Premium Grade Hydraulic Fluid with the correct viscosity will provide maximum protection of the pump and you will get maximum performance. Using any of the other acceptable oils will not hurt the pump as long as they are the correct viscosity for the temperatures you are operating in.

 

[nobull1]

You guys got me thinking. I figure the hydrostatic pump is the most expensive item in the system and should be the item with most specific requirements.
I got the number off the pump in my 763, It is a Sauer Danfoss M91-35916 CCW. I called Sauer's Customer Service Dept and they identified it as a Series 40. They directed me to the Sauer Danfoss website and told me to open the Hydrostatic Propel Products and then the Series 40 Axial Piston Pumps and Motors. There you can down load the Service Manual and Technical Information on the pump.
They also directed me to a Technical Information on Hydraulic Fluids and Lubricants publication that is available from the same site under:
Sauer-Danfoss then Systems/Applications Technical Information then Technical Information (TI) then Hydraulic Fluids and Lubricants TI_11-2007_RevGC.pdf
Page 21 states:

Sauer-Danfoss hydrostatic components may be operated with a variety of hydraulic fluids.
The rated data which we publish in our Technical Information and Service Manuals are based on the use of premium hydraulic fluids containing oxidation, rust, and foam inhibitors. These fluids must also possess good thermal and hydrolytic stability to prevent wear erosion, and corrosion of the internal components. For some applications good anti-wear additives are required.

The following hydraulic fluids are suitable
:

• Hydraulic Oil ISO 11 158 - HM (Seal compatibility and vane pump wear resistance per DIN 51 524-2 must be met)
• Hydraulic Oil ISO 11 158 - HV (Seal compatibility and vane pump wear resistance per DIN 51 524-3 must be met)
• Hydraulic Oil DIN 51 524-2- HLP
• Hydraulic Oil DIN 51 524-3 - HVLP
• Automatic Transmission Fluid ATF A Suffix A (GM)
• Automatic Transmission Fluid Dexron II (GM), which meets Allison C-3 and Caterpillar TO-2 test
• Automatic Transmission Fluid M2C33F and G (Ford)
• Engine oils API Classification SL, SJ (for gasoline engines) and CI-4, CH-4, CG-4, CF-4 and CF (for diesel engines)
• Super Tractor Oil Universal (STOU) special agricultural tractor fluid

There are also charts that detail the oils and the temperature ranges that are acceptable for those oils. I phoned their Technical Support Line to clarify a couple of points:
1. They first recommend Premium Hydraulic Fluids and told me Mobil DTE 15M is very good. I live in southern Minnesota and they recommended
ISO 46 for the temperatures we normally see 100 to 0 degrees F.
OR
ISO 32 if we were operating a lot in the -10 to -20 degrees F.
2. He stated while any of the acceptable oils listed above will work, choosing the appropriate viscosity for your climate is very important and keeping the oil clean is critical.
3. Mixing the mineral based oils is not a significant issue since totally draining the system is not cheap or easy. However he stated if you want to change to some of the exotic or biodegradable oils you can have some nasty results if the system is not totally drained and flushed as some of these oils are incompatible with the mineral based hydraulic fluids.
4. If you choose to use the acceptable API Engine Oils and Automatic Transmission Fluids be aware that the oils have a high shear-ability which results in the oil performing at a much thinner viscosity under high loads. For example SAE 10W oil under high load will perform like an SAE 6W under high load. Too thin and you can start having parts rubbing together.
5. Using a Premium Grade Hydraulic Fluid with the correct viscosity will provide maximum protection of the pump and you will get maximum performance. Using any of the other acceptable oils will not hurt the pump as long as they are the correct viscosity for the temperatures you are operating in.

Good research....lots of good info.

 

[Tazza]

Good research....lots of good info.

Very good info, still not sure just what oil i should be running in my *new* 751.....

 

[Land-Tech]

fishfiles Can you get a copy of the bulletin and post an image of it for all to see.
Like it was stated before Bobcat doesn't publish what grade their branded oil is. But since they only have one grade that they sell we can assume that it's an all weather multi-grade oil. Very few oil manufacturers make a multi-grade hydraulic oil and most are branded by one of the farm equipment manufacturers, John Deere Hy-Gard, Kubota Super UDT and Amsoil Synthetic Tractor Hydraulic are the couple I found.
Using the wrong viscosity oil can lead to component failure. Too thin and it thins out at high temp and parts wear quickly. Too thick and pumps cavitate.

I'm changing hyd fluid in my Gehl today, going from Iso 32 to iso 46 which is reccomended.
I did a search to find out just what the grades mean. the numbers do reflect visocity but from what I understand,a more important referance for us is the viscocity index, which is the ability oil has to keep it properties at high or low temps.Muti wt oils have a higher VI than single wt oils they keep properties in extreme condition better.(anti-wear and lubrication along with the ability to flow) older hydralic systems with gear pumps can use just about anything with out a problem but all the info that I looked up reccomend that if you have piston pumps or low flow high pressure systems (newer minis) that you should use an oil that has a vi of over a 100.
The VI can be from 0 to 1000's The higher indexs are for extreme uses,(comppressors,turbines and space shuttles) Systems that have high hours or may be worn need either a multi- weight or bit higher viscocity to offset the internal leakage that comes from wear.
I'm with Tazza on the muti-grades, they work great. Warm you machine up to normal temps and notice what kind of sounds it makes when you run it, perferably after you changed the filters. Then work it hard and see if you notice a diff. If it makes a lot more noise maybe you can go to a better grade. again the iso or sae number is not the Vi. you will find the Vi in the fine print on the can.
There are other properties that oil needs that I could go into but I got to go to work. Will let you know if this makes a diff on my machine thanks scott