Hydraulic fluid instead of Motor oil hlp

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Dhandy

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Joined
Apr 25, 2008
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I just recently blow a hose on my right hydr motors .I replaced the hose and put hydrolic fluid in the Hydraulic system .Now I find out that it uses motor oil . I have put about 5 hours on it since I put the Hydraulic oil in the system. Question is do I need to remove this and put motor oil in and 2 how do I flush the system. It is a 1999 bobcat skid steer 763 Kubota diesel. help
 

pondfishr

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Oct 11, 2005
Messages
216
What kind and how much hydro fluid did you use in your machine? My 743 manual lists Bobcat hydraulic/hydrostatic transmission fluid P/N 6563328 or 10W-30 or 10W-40 SAE motor oil. I have read here that most hydraulic fluids are too thin for the Bobcat specifications. There are a number of posts here addressing the same question. You should be able to do a search with hydraulic fluid and oil and get a number of hits. For flushing the system I don't think there is a complete method. You run the machine with the system breached until you hear the pumps whine. Shut the machine down and add fluid. You have to do this a number of times to completely flush the system but that is the procedure. Check old posts for more and I am sure some of the other members will help out too.
 

Tazza

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What kind and how much hydro fluid did you use in your machine? My 743 manual lists Bobcat hydraulic/hydrostatic transmission fluid P/N 6563328 or 10W-30 or 10W-40 SAE motor oil. I have read here that most hydraulic fluids are too thin for the Bobcat specifications. There are a number of posts here addressing the same question. You should be able to do a search with hydraulic fluid and oil and get a number of hits. For flushing the system I don't think there is a complete method. You run the machine with the system breached until you hear the pumps whine. Shut the machine down and add fluid. You have to do this a number of times to completely flush the system but that is the procedure. Check old posts for more and I am sure some of the other members will help out too.
I have always used motor oil but recently there have been a few posts about using hydraulic oil. The main problem is with hydraulic oil there are different grades. And yes, some hydraulic oil is indeed too thin and can cause pump damage due to lack of lubrication. If you only added a small amount of hydraulic oil i see no problem, if you used a LOT you *may* have a potential problem. The hydraulic system holds around 25-30 liters or there abouts, including the reserve tank.
I still need to find out just what grade Bobcat recommends for hydraulic oil but i was always told 15W30 20W50 etc were fine.
 
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Dhandy

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Apr 25, 2008
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I have always used motor oil but recently there have been a few posts about using hydraulic oil. The main problem is with hydraulic oil there are different grades. And yes, some hydraulic oil is indeed too thin and can cause pump damage due to lack of lubrication. If you only added a small amount of hydraulic oil i see no problem, if you used a LOT you *may* have a potential problem. The hydraulic system holds around 25-30 liters or there abouts, including the reserve tank.
I still need to find out just what grade Bobcat recommends for hydraulic oil but i was always told 15W30 20W50 etc were fine.
Thanks for your help I call Ford or New Holland and they told me that there fluid was not rated for the bobcat so I will flush the system. The hydra fluid was only in for like 7 hours of run time. So I think I will go with the 10w40 would a 30w work or a 15w 40
 

WebbCo

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Sep 19, 2006
Messages
177
Thanks for your help I call Ford or New Holland and they told me that there fluid was not rated for the bobcat so I will flush the system. The hydra fluid was only in for like 7 hours of run time. So I think I will go with the 10w40 would a 30w work or a 15w 40
I get this guestion 5 times a day...and I wish there was a straight answer for all but there is not. Some of the older machines called for motor oil or Bobcat Black gold oil. Bobcat has since started changing all manuals to read Black gold. Heres how we handle it at my place of biz,
If you need to top off, say 1 maybe 2 gal, and dont have black gold available, use the motor oil, Reason...some oil is better than no oil. Motor oil is much more refined, than say AW32 or lower, AW46 is a closer match to black gold but still not perfect. Taz stated this correctly, the plates need the bobcat fluid or accelerated wear can occur. AW46 in 2 gal or less is fine also, its just after you have diffenent fluids in different attachments, hose leaks, etc you can sure dilute the mix in your machine, and with many different people adding fluids at different times you may not have a clue whats really in your machine, Rental units come to mind here.
I would say if you have had a leak for a while and have dulited the mix over time, do yourself a favor and change out everything at your next service, your money is better spent on the right fluids rather than the new drive motors and pumps. I wished I had all the technical b/s to give you but alas Im only a dumb parts guy! My life is spent trying to find parts for machines with out a vin number, or having the guy who states he has a CASE X75 Bobcat...or the other favorite of ours the Ultra rare John-holland, and not to be confused with the brother of that machine the New-Deere. Its no wonder I look 80 years old and havent even broke 50 yet.
Mark
 

Tazza

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Staff member
Joined
Dec 7, 2004
Messages
16,829
I get this guestion 5 times a day...and I wish there was a straight answer for all but there is not. Some of the older machines called for motor oil or Bobcat Black gold oil. Bobcat has since started changing all manuals to read Black gold. Heres how we handle it at my place of biz,
If you need to top off, say 1 maybe 2 gal, and dont have black gold available, use the motor oil, Reason...some oil is better than no oil. Motor oil is much more refined, than say AW32 or lower, AW46 is a closer match to black gold but still not perfect. Taz stated this correctly, the plates need the bobcat fluid or accelerated wear can occur. AW46 in 2 gal or less is fine also, its just after you have diffenent fluids in different attachments, hose leaks, etc you can sure dilute the mix in your machine, and with many different people adding fluids at different times you may not have a clue whats really in your machine, Rental units come to mind here.
I would say if you have had a leak for a while and have dulited the mix over time, do yourself a favor and change out everything at your next service, your money is better spent on the right fluids rather than the new drive motors and pumps. I wished I had all the technical b/s to give you but alas Im only a dumb parts guy! My life is spent trying to find parts for machines with out a vin number, or having the guy who states he has a CASE X75 Bobcat...or the other favorite of ours the Ultra rare John-holland, and not to be confused with the brother of that machine the New-Deere. Its no wonder I look 80 years old and havent even broke 50 yet.
Mark
I can imagine that, especially with a pesky Aussie that keeps bothering you about parts :)
Over here EVERYONE calls their skid steer a "bobcat" i went to buy a used bucket off a *bobcat* it was off a Toyota husky! i said thats not a REAL bobcat, he goes it sure is! He hates bobcat but calls his machine a bobcat, go figure....
As for the oil, i really want to work out just what i *should* be running, i have my entire system drained and would like to put the rite stuff in. I have never had an issue with motor oil in the past and its cheap too.
 

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