240d Runs Fine On Used Motor Oil - PeachParts Mercedes-Benz Forum

#1 02-17-2003, 10:31 AM

I have been fascinated with the idea of running my diesel on other alternate fuels besides that of Diesel which is now capping out at $1.69 per gallon. I work at an automotive dealership and have more than ample supply of used motor oil. I picked up a nice 240D with 74000 miles and have been increasing the amount of used motor oil to my mixture of diesel. Im currently running about 60% oil to diesel and while I dont really see why, it seems to run with a little more power the more oil i add. There has been no increase in smoke at all. It seems to fire off and go to a smooth idle a lot faster in cold weather. The coldest i have cranked in is 17 degrees. I make a 70 mile round trip daily to and from work is why i bought the car...might as well wear out an older car than a newer car... The $500 price tag wasnt that bad either, so being that I got it cheap, I feel justified in experimenting with it. What I would like to know is there anyone else out there supplementing fuel with used motor oil...if so what kind of ratios have you achieved? This summer I am going to try 100% used motor oil and see what happens. Comments?

Wasuchi · #2 02-17-2003, 10:51 AM

I'm assuming you filter the used oil before putting it in the tank? If so, how do you filter it?

#3 02-17-2003, 11:18 AM

Yes, you most definitely must filter it.

I used to bother with pouring my drained oil through several layers of muslin, then pouring it in the tank, no more than about two quarts per tankful. It worked great, but was just too much of a hassle to bother with.

A major rental truck company filters drained oil then pours it in the fuel tanks. The difference here is that even five gallons or so of filtered, drained oil is dilluted well in the 250 gallon tanks.

Have a great day,

rickg · #4 02-17-2003, 11:29 AM

I'm finding this even more interesting than using veggie oil. Used motor oil would be so easy to come by, and I don't see the potential of damage to the injection pump, ect as I've heard mentioned with veggie oil.

#5 02-17-2003, 11:30 AM

I considered that at first and then realized that the oil is constantly filtered while it is in the car that it came from so I bypassed that step. Also most manufactures of later model cars provide a magnet in the oil pan or on the oil pan plug itself that captures any metal particles...which are virtually nonexistant in cars over 10000 miles anyway. I am keeping a watch on my primary and secondary fuel filters but they dont seem to be stressed or show any signs of clogging. By posting this I am hoping to find someone that has had a problem so I will know when to quit...but as it stands everything is a go.

rwthomas1 · #6 02-17-2003, 05:43 PM

I would certainly filter it again before using it!! A simple system can be easily made with an electric fuel transfer pump and a standard auto filter like a ph8a. At the very least a large truck-type fuel filter added before the two MB filters to catch any crap thats there. I wouldn't run more than 25% used oil just because I don't feel comfortable running a diesel on such a high-viscosity fuel. I start thinking about over-stressing IP parts.... RT

#7 02-17-2003, 05:54 PM

This is a very interesting thread. I have several gallons of used oil laying around, and I might give this a try sometime.

DieselAddict · #8 02-17-2003, 09:07 PM

This is madness!

This is something I'd never consider doing to a car that I plan to keep.

diesel don · #9 02-17-2003, 10:03 PM

I did this last spring a little. Not even 10%. Worked fine.

I find 60% an incredible ratio. If this could be sustained over a long period of time, it'd be amazing.

Keep us posted.

I was going to wait until it warmed up, but now I'm going to filter it and go for it.

Thanks a bunch,

Don

#10 02-18-2003, 08:02 AM

RT,

You have a good idea with the PH8, but it is not a fine enough filter element. I can't remember what the trucking company was using, but it was VERY fine.

A filter arrangement can be made with some buckets and several layers of heavy cloth. Pour the oil so that it will gradually flow through the cloth.

wfdiesel,

The filtering that is done while the oil is in the car is totally insufficient. You must remember that the holes in your injectors are much smaller than a human hair. I have heard of truckers just pouring the oil in their tanks, and it caused lots of problems.

DieselAddict,

There is nothing at all outrageous about this as long as you FILTER the oil. The national rental truck company that I know has done and I fully expect are still doing this, are extremely scientific in their maintenance and operation approach. They have a large laboratory and research department that is constantly testing all sorts of things, and probably learn more about the maintenance and operation of diesel trucks than any manufacturer. If they weren't doing this with confidence, I might also think it was outragous.

Also, remember, diesel fuel is nothing but lightweight oil.

Have a great day everyone,

car54 · #11 02-18-2003, 08:53 AM

The wear metals in the oil will cause elevated injector and fuel pump wear. Keep in mind fuel pressures can reach 4,000+psi and the components pressurizing this fuel are very precise and require clean fuel. I would recommend installing a two micron final filter in-line with the original final filter if you plan on keeping the car.

With that said, I will agree that a $500 car is the best to experiment with, and you will probably save $500 in fuel costs prior to any measurable wear occuring inside the fuel pump or injectors. I wouldnt do this to a car unless I considered it junk at that point and had another reliable way to get to work. But the money saved is considerable. I know when I worked for the marine industry some of the large Sulzer, Wartsila, Niigata, and DDC/MTU diesels would actually have a setup that would allow them to run off their own crankcase oil, and they would measure how much was removed and constantly replace it until the oil had basically been flushed completely. Of course these engines burned bunker oil that was the consistency of grease at room temp, but its the same basic theory, although I can assure you they took filtration extremely seriously, for the oil in the crankcase, the oil being burned, and the fuel being burned.

Good luck, keep us updated on how it works.

Stevo · #12 02-18-2003, 11:30 AM

Very interesting.

Would there be any problem burning synthetic oil I wonder? I would think not but .....

DieselAddict · #13 02-18-2003, 12:34 PM

LarryBible, actually this idea is not new to me and I'm aware that diesel is just another hydrocarbon like oil, but with a shorter chain and thus less viscous than oil. I don't have doubts that a diesel engine can run on oil. But I don't think anyone will convince me that it's as safe as using diesel, even if you filter it. You still have the higher-than-recommended viscosity to deal with. Not to mention that diesel fuel is cheaper than motor oil and I don't have vast quantities of used oil lying around, but that's not the main issue.

dabenz · #14 02-18-2003, 01:20 PM

1 gal oil to 100 gal fuel is a common ratio in the trucking industry, and has been for as long as diesels have been in the trucking industry (about 50 yrs). Keep in mind they have more substantial fuel filtering systems, too. The professional filtering companies came about because of the pollution folks (tree hugger and government types).

An old school cold start trick is to spray oil into the intake manifold in lieu of glow plugs or ether. There are still small (sailboat) marine engines that do it this way, and the manifold is built with ports you can open.

wfdiesel is proving again that the 220D/240D is one of the best engines ever built. Can't wait to find out his limit of fuel filter plugging!

rwthomas1 · #15 02-18-2003, 01:42 PM

Larry, I agree on needing a finer filter but I was mainly concerned about catching any crap that ended up in the used oil as it was drained/stored. Hydraulic system filters are available in many micron ratings so it would be easy to setup a system that first used a ph8a and then a 2-micron hydraulic filter, pushing the oil through them with an electric pump. Easy to build and fairly cheap. RT