USED OIL IN A DIESEL?

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Does anyone here use used motor oil or used cooking oil, straight, not filtered in their diesel engine? Brothers friend has a older or early 90's dodge with the 2valve cummins in it and uses this without any noticeable problems. Would doing this harm anything or do any damage? Other than it being smokey I dont think so.


correct me if I am wrong and any advice, opinions and thoughts are greatly appreciated.
 
I put in two gal of used oil in my Isuzu NPR when I fill it up.
when I refuel I normally add 28 gal plus my two of used oil, the truck holds 33 gal.

It seems to have no effect on the operation, this truck is a 1996. I dont think I would do it on a more modern diesel engine.
 
The vehicle brothers friend has is a 90' dodge dually with 2 valve per cylinder, cummins diesel. I have read those pumps on those cummins would pump sludge if they had to!


I think he'll be fine using straight used oil and cookin oil myself.
 
Yep, the old Bosch style inline injector pumps are pretty right with used oil/cooking oil, I just wouldn't run any where near 100% is all.

New diesels with rotary pumps don't like too much of a viscosity increase, as the thrust increases, while the thrust bearing lubrication decreases.

Common rail and DI, I'd avoid too much used oil.
 
Well my brothers friend is doing just that; using straight used motor oil and cooking oil without any problems. He's put 120k on the truck since he has had it and still using used oil and used cooking oil. I dont see a problem even with that old 2 valve cummins myself. Heck, we ran our WAUKESHA diesel v-10's on a mix of diesel, kerosene and old cooking and used diesel engine oil without a prob


adam
 
I run my '01 24-valve on up to 7% waste motor oil without problems. It doesn't smoke at this level of WMO concentration. The combustion noise from the engine seems lower when using WMO. Fuel economy is basically the same as on straight diesel. I only add WMO if the weather is above freezing. I save my oil through the winter and begin using it in the spring. I won't run waste oil out of my diesel due to concern for soot causing wear in the pump and injectors. I have a fuel pressure gauge so I can monitor if the filter is clogging.
 
I use 75% umo in a 82Volvo diesel(370000km),hard to start when cold.I run it thru a centrifuge,and heaters on injector lines.No problems so far.
 
Depends on what kind of diesel engine you are going to put the WMO in?

Some diesel engine does not like it. The older they are, you are probably fine like the one your friend is using it.

So, we need to know that information.

You probably don't want to put it in modern diesel like Duramax with a price tag of more than $40k.

I know, in my case, the GM 6.5L TD does not like it. The Optical Sensor in IP is not very cooperative with dark fuel.
 
Yeah, I know about the newer diesels, but a friend of mine that works for a energy company; that has a 03 chevy quad cab diesel found that using low ash bar and chain oil Super Tech oil was and isnt bad for the engine at all.
 
UMO is filtered to death while in service before draining. Unless it saw contamination after it leaves the oil pan, I don't see why it needs to be filtered.
 
Originally Posted By: Kestas
UMO is filtered to death before draining. Unless it saw contamination after it leaves the oil pan, I don't see why it needs to be filtered.



In the newer common rails pushing 25kpsi at the injector, even a minor amount of contamination can cause erosion of the injector tip/nozzle.
 
The friend of my brother and myself has two very high micron filters also on his truck, that he changes often also. I wouldnt worry much about any contamination or much of that as Kestas said.
 
Originally Posted By: Silver_civic
Yeah, I know about the newer diesels, but a friend of mine that works for a energy company; that has a 03 chevy quad cab diesel found that using low ash bar and chain oil Super Tech oil was and isnt bad for the engine at all.


You are flip floping between used oil and new oil????

New oil is fine, it is good for oil lubricity as long as it does not have crudy color.

I put new oil or 2 cycle oil for added lubricity to ULSD.

Just a note.
 
Thats what I meant about using 2cycle, as I said my friend uses that as its also low ash. Didnt know that meant I was flip flopping between new or used also.


adam
 
ive always been under the impression that used cooking oil even filtered has a "grit" to it, i wouldnt think that would be a good thing in the long term
 
If I were going to run used oil through a diesel engine I would do the following:

Push all used oil through a Bypass filter set up.
Store clean oil in jugs that match a 5% blend to clean fuel fill up.
Add appropriate cetane/fuel conditioner additive as well.

I am not sold on straight used or vegtable oil use at this time. I would if the diesel supply was exhausted and I needed to drive. And this could be the case someday.
 
My shop where I work may start using the old oil and atf and such to heat the shop. Guy I work with has a 93 or 94 dodge diesel truck and he takes a lot of our old oil off of us, and hits a few trans shops and uses that, he says the bar and chain oil helps. If someone can use old motor oil, atf, ps fluid, etc mixed in with "real diesel"(which you can get in my area, as lil more expensive) then they should use it.
 
I drove a diesel rabbit for 2 years during the 2006-7 oil price hike. I consumed plenty of used motor oil. However, I filtered it with a Motorguard 0.5 micron filter, by siphon/gravity.

The oil was drawn from a barrel that had settled for quite some time.

The little rabbit actually ran better, the injectors remained clean and when the car was junked, the engine was removed and disassembled. Everything looked clean and normal.

However, the reason for taking the car off the road was that it would not start anymore. The engine was worn out. It was starting on one cylinder when I got it, so compression was quite low to begin with. (new glow plugs)

Eventually, after about 40,000 miles, the engine lost enough compression that starting in Florida winters was near impossible.

Did the waste motor oil contribute to engine wear? I have no way of knowing.
 
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