If I wanted to dump some used motor oil in my fuel tank,,,,,,,,,

[davidlee]

Granted it would be filtered and it would only be about 1 gal or so for maybe a half tank of fuel, that shouldn't hurt anything should it?
I am talking about Dino oil by the way.
And if its okay to do with dino, My next question is, could you do the same thing with synthetic?

Why???? because I dont like dumping oil into the ground and I dont like carting it back to the auto part store. especially if my car will use it for a second go around.

[connerm]

Not wanting to dump it or recycle it are two bad reasons to dick around with filtering a gallon of used motor oil for use in a Mercedes injection pump and engine.

[MS Fowler]

To me, such a small amount isn't worth the risk. You will save about $4--the cost of a gallon of diesel. You risk--plugging filters, ruining injection pump and injectors.
Now if you were running fully on used MO--and drove 20,000 mile free of fuel cost, then the cost of the pump and injectors might even it out---but I doubt it.

[Left Coast]

Why don't you just put it in a used milk jug and put it out for curbside recycling, like everyone else in Portland does?

[ChiefRider]

Do you heat with oil? Put it in your heating oil tank.

[dude99]

filter it and pour it in your tank. It'll be fine

[97 SL320]

Ugh, this kind of thing just won't go away.

Lubricating oil used in a engine isn't designed to be burnt and we have changed the oil because it is contaminated, why would you want to run it through a injector pump with clearances much smaller than a crankshaft
? Same goes for ATF or rear end lube.

Lube oil has additives that leave ash , carbon and other bad stuff when burnt. Find someone that has a waste oil heater and ask then what kind of junk is left in the combusion chamber and how often they need to clean it out. Do the same for a heater that uses fuel oil. ( Fuel oil / heating oil is diesel fuel dyed red )

Sure you can get away with burning old oil but at what potential cost? If you got the used motor oil clean enough, would you dump it back into your crankcase?

[Volker]

you guys are nuts, just drain it into your pan and pour straight in the tank. Filtering? there is a filter right before the injection pump!

[Mark DiSilvestro]

Maybe 4 - 5 times in the past six years, I've added a gallon of used oil to a tankfull of diesel on my W123s. Either the relatively clear motor oil or ATF from one of my gassers that sees lots of highway miles. Never the sooty diesel-oil though.
Did have a problem one time, plugging the primary filter on my first 240D. Changed that filter and it was fine.
In warm weather, I used to have signficant pinging (nailing?) with my latest 240D under part-throttle. That noise went away after adding a gallon of ATF from my '96 Camry.

Happy Motoring, Mark

[vtmbz]

Think for a minute what the pistons and valves look like on an engine that is burning lots of crankcase oil, all gummy and nasty and carboned up, right?

So why simulate that on your nice tight engine by adding oil to the fuel? A gallon of oil in a tank of fuel would be like an engine burning a quart of oil every 100 miles of driving. Youre taking a good engine, and making it duplicate a worn out one....

[pawoSD]

I will never understand why people want to do this. It causes super-pollution when burned, its bad for the injection pump and injectors, and saves you about $3 in diesel for all these downsides.

Pouring it into the ground?!?!?!? a quart of oil can contaminate 2 MILLION gallons of water. Why would putting it in the ground even cross someone's mind?!

RECYCLE THE OIL PROPERLY.


I'll never forget when someone told me they always bury their used oil on their property. Ironically, they had well water from their own property, which they drank. Amazing. Sometimes there's an explanation why people get cancer...

[ruchase]

Originally Posted by pawoSD

RECYCLE THE OIL PROPERLY

At the very least, think about the financial risk you are taking for not responsibily disposing used motor oil. The liability for dumping hazardous waste is unlimited.

[davidlee]

How did I know this would stir up the bee's nest, 1st off I dont dump used oil into the ground, I live in Portland and thats something that is punishable by death around here, 2nd I wasnt talking about running straight motor oil in my tank, just a little bit, and only every once in a while, I dont have barrels of used oil lying around that i dont know what to do with, Im talking about a gallon or two every few months, and 3rd (which I didnt mention before) its not used (diesel) oil, I run synthetic in my Diesel's now, since some guy on here that had thousands of posts told me basically I was stupid because i wanted to change out one of my lifters because it makes noise occasionally when its cold, I was told "waste of time", just spend twice as much every oil change and it will go away, 15K miles later on Delo400LE synthetic, it still makes noise sometimes. and 4th, Im not hell bent on running used oil though my fuel, I just wanted to know what potential damage it could cause.
Why would injection pump failure be caused by running a little oil through it?
Im not arguing, I just dont know, could someone please explain without talking to me like I'm some guy trying to ruin my car and my neighbors water supply.

[Stretch]

I think many countries use waste oil as heating fuel - that seems to me to be less risky than trying to use it as automotive fuel.

[ChiefRider]

Originally Posted by davidlee

Why would injection pump failure be caused by running a little oil through it?
Im not arguing, I just dont know, could someone please explain without talking to me like I'm some guy trying to ruin my car and my neighbors water supply.

You deserve an appropriate answer.

Used diesel lubricating oil contains LOTS of particulate contaminant. Running even just a gallon thru your fuel system once in awhile will really shorten your fuel filter life. Your filter won't remove all the crap; some will make it into your IP, which is a fairly sensitive instrument. It is unlikely that this dilution of your lube oil will cause a failure, but it will contribute over time to increase the potential for a problem.

The bottom line is this:

The upside is you save a couple bucks for the "free" gallon of fuel.

The downside is you contribute to premature wear, and add an infinitessimaly small amount of pollution into the air.