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Cat D5C dozer hydraulic fluid topped off with diesel

edbemis

Member
Joined
Jan 3, 2022
Messages
10
Location
Spencer MA
Hi folks,
Sadly, an employee topped off the hydraulic fluid with diesel, instead of filling the fuel tank on my Cat D5C dozer. Fortunately, it has not been used, started, or moved since he did this a few hours ago. I'm thinking I should just siphon out the tank, and refill with actual hydraulic fluid. Allegedly it's about a 15-gallon tank. Does that sound like a reasonable approach? I don't see an easily accessible drain port. Do those wiser than me, and that's almost anybody, have a better idea? Is it going to need "rinsing" with hydraulic fluid before refilling? Thanks very, very much!
Ed

(Yes, the photo shows the *correct* place for the diesel to go in!)
 

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reganj

Senior Member
Joined
Jan 1, 2024
Messages
354
Location
Central Ms
I believe you are going to happen to open the hatch door that has Caterpillar on it and you will find the drain for the hydraulic and diesel tank.
Drain the hydraulic tank completely, and it is preventative maintenance to open the drain for the diesel and hydraulic every so often until clean diesel or hydraulic fluid comes out if you have any water or contaminants in the tank.
Best practice is to park on a slight angle and let sit overnight so the contaminants settle where the drain is located.
 

Deimos

Well-Known Member
Joined
Nov 8, 2024
Messages
237
Location
RUS
Unfortunately, this happens often, inexperienced operators confuse the fuel and hydraulic filler necks)))
If the machine has not been running, then you just need to drain and fill the oil into the tank.
 

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Welder Dave

Senior Member
Joined
Oct 11, 2014
Messages
18,181
Location
Canada
I put a hose on a rotary barrel pump and put the hose in the filler neck to get the hyd. oil out of my 931B that looks very similar. Kind of a pain draining from the drain above the track. I got the last bit out from the drain. If the machine never ran, the filter should be fine but it's easy enough to check. I can't remember if the filter is fully open to the reservoir.
 

Mcrafty1

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Joined
Oct 12, 2019
Messages
586
Location
Central Maine
Occupation
Earth work
How low was the hydraulic tank when the fuel was put in? What I'm getting at is if there was only around a gallon of fuel mixed in I wouldn't worry about doing anything, At least not until hot weather came back around, by then you may have already added more hydraulic to the tank which would bring it back closer to the original viscosity. Here in Maine when cold weather comes around some people cut their hydraulic with fuel....in small amounts, like a gallon in 15. If you are worried about it mixing in don't, both are petroleum based and mix fine. jmho
 

Welder Dave

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Oct 11, 2014
Messages
18,181
Location
Canada
I'm not sure if the diesel would sit on top of the oil or not. Thinking you could maybe pump just the top portion of the reservoir.
 

LCA078

Senior Member
Joined
Sep 29, 2019
Messages
741
Location
Austin, TX
While I'm not recommending to do this, I know a handful of folks who wouldn't hesitate to burn the contaminated hydraulic oil in their diesel engines as hydraulic oil is "clean" compared to most used oil. For me, it's cheap insurance and a huge piece of mind to toss the 15 gallons of hydraulic oil and get fresh Cat oil. Like said above, drain/siphon the tank and replace the filter and you're good.
 

edbemis

Member
Joined
Jan 3, 2022
Messages
10
Location
Spencer MA
How low was the hydraulic tank when the fuel was put in? What I'm getting at is if there was only around a gallon of fuel mixed in I wouldn't worry about doing anything, At least not until hot weather came back around, by then you may have already added more hydraulic to the tank which would bring it back closer to the original viscosity. Here in Maine when cold weather comes around some people cut their hydraulic with fuel....in small amounts, like a gallon in 15. If you are worried about it mixing in don't, both are petroleum based and mix fine. jmho
Unfortunately, he put in about 7 gallons, filled above the sight glass pretty much to the top. I greatly appreciate your insight.
 

edbemis

Member
Joined
Jan 3, 2022
Messages
10
Location
Spencer MA
I'm not sure if the diesel would sit on top of the oil or not. Thinking you could maybe pump just the top portion of the reservoir.
I was wondering the same thing. Especially after I found out the Cat fluid was $175 for a 5-gallon pail, I thought about the separation of layers more!
 

Nige

Senior Member
Joined
Jun 22, 2011
Messages
38,757
Location
G..G..G..Granville.........!! Fetch your cloth.
I was wondering the same thing. Especially after I found out the Cat fluid was $175 for a 5-gallon pail, I thought about the separation of layers more!
Why do you feel the need to put Cat-branded oil into it.?
Any good-quality (major oil brand) SAE10W hydraulic oil will work just as well.

you have the advantage that the machine was never started. My thought would be to drain the tank (as others have pointed out the tank drain valve is under the RH fender) and drain the contents. Fill with new oil and go on your way.
 

LCA078

Senior Member
Joined
Sep 29, 2019
Messages
741
Location
Austin, TX
If that employee is still with you....make him/her drain the tank, dispose of the contaminated oil, go to the store and buy new hydraulic oil (with company credit card) and change the filters. That should be "payment" for the mishap.

I get mistakes happen but there's consequences too.
 

edbemis

Member
Joined
Jan 3, 2022
Messages
10
Location
Spencer MA
If that employee is still with you....make him/her drain the tank, dispose of the contaminated oil, go to the store and buy new hydraulic oil (with company credit card) and change the filters. That should be "payment" for the mishap.

I get mistakes happen but there's consequences too.
In this particular case, I don't want to go from bad to worse. I learned my lesson. That person doesn't get tasked with anything remotely difficult anymore.
 

edbemis

Member
Joined
Jan 3, 2022
Messages
10
Location
Spencer MA
Why do you feel the need to put Cat-branded oil into it.?
Any good-quality (major oil brand) SAE10W hydraulic oil will work just as well.

you have the advantage that the machine was never started. My thought would be to drain the tank (as others have pointed out the tank drain valve is under the RH fender) and drain the contents. Fill with new oil and go on your way.
Some of the info from CAT made a big deal out of the oil having >900 ppm zinc in it. But your comments are noted. One of the guys at the dealership said if it were his old machine, he would do as you suggest. I was thinking of using a zinc additive also. Good or bad idea?
 

pittsburgh cat man

Senior Member
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Oct 20, 2024
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1,179
Location
saltsburg pa
All I can say about that is in all my time at a cat dealer the only trucks I ever saw delevering oil to our bulk tanks was a local oil company as far as additives the only time we would use the additive was when there was noise or cylinders were jerking
 
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