Running WMO

[Redneckintraining]

I was running WMO(waste motor oil) in my 89 W250 CTD.The oil was cleaned by running it through a centrifuge.Then before it got to the injection pump it passed though a heat exchanger.Which was an oil cooler surrounded by hot coolant.The setup worked great for a couple of months.Then everything went to poo.The engine oil was simply to thick to flow through the injectors properly.Rather than an atomized mist or spray, I had liquid droplets.Eventually the oil started coking up the tips of the injectors.The internal bits of the injectors quickly got worn down from the extra effort to "pop".It got to the point that the truck was very difficult to start, once it got running it idled piss poor and was very sluggish. It constatly smoked.A faint trail when moving and plums of smoke when idling.The injectors were toast.600 bucks later for rebuilt injectors.Aint life grand but I still had some oil in the tank. the new injectors were fine for about two weeks then I started to get the light hazing going down the road.It smoked at idle when cold until the oil was gone from the tank,now the truck is mostly happy now that Ive run about 3 tankfuls of diesel through her.Still need to get the injectors cleaned and pop pressures reset.BTW I was running close to 85-90% oil.

All that because the viscosity of the used oil was just to damn high. diesel at room temp has a viscosity of 1.4-4.1 cst,while oil is 100.At 212*F oil is 10 cst.
I did some experiments today to see if I could thin the oil down with something to get it in the range of diesel.I set up a funnel with a coffee filter and poured a known amount of whatever through and counted how long it took to empty.

diesel rushed straight through the filter. it took about 55 seconds for most/all of the diesel to leave the funnel.

I wanted to use my old oil but all of mine had been sitting outside in 55 gallon drums and was mostly water now.So I used a qt of sae 50 wt. the used oil would have been a little thinner but whatever.
I started with a small about of mineral spirits in the oil but that didnt do much.So for the next test I mixed in 25% mineral spirits in with the oil(1/4 cup MS, 3/4 cup 50wt) that flowed through the filter in about 7 times slower than the diesel.Or about 10.5cst. Next test was 50/50 diesel and 50 wt. that flowed through the filter in about 4 minutes.Or a viscosity of about 5.

The fuel will thin down more that in reality because by the time the fuel passes through the lift pump,the IP and the injectors, its proablly about 160-200*F.

Does anyone know of any stronger solvents that wont be too corrosive that could thin the oil down without costing to much?mineral spirits at $10 isnt cheap. diesel is $3 bucks a gallon so its cheaper but not ideal.

Would acetone work?Ive heard about gasoline being used but im a bit leary..any other ideas?

I would love to go on long trips for almost free.run mostly engine oil with a gallon or two of some solvent to the thin the mix down...

OH, and my test vehicle would be a 83 mazda B2200 with a perkins 2.2L diesel.Rather than buying a new set of injectors for my dodge if it doesnt work out...

[diesel freak01]

honestly i wouldnt use anything but pure diesel to thin the oil down, i know what mineral spirits does to oil so it has to break it down and that how your pump loses lubricity and would break down the seals

[Redneckintraining]

yea but the oil even when its thinned down is still way more slippery than ULSD.

[VMacKenzie]

The main concern with gasoline is running hotter, but I have run about 250 gallons of gasoline through my '98 with no ill effects so far. I have mixed up to almost 20% gas with my vegetable oil and diesel mix, at that percentage there was no noticeable effect on how the engine behaved. I heard you can get away with up to about 30% gas in a Cummins provided the lubricity is there, but I would give yourself at least 100-150F more EGT margin at the high end to keep from damaging pistons, rings or injector tips (I try to keep under 1050F when I have a lot of gas in the tank).

You are running way too high percentage of eng oil, part of the problem is engine oil is designed to maintain a stable vis across a wide temp range, meaning heating it won't thin it very well compared to vegetable oil.

I would try your viscosity experiment with 30% gas 60% oil and 10% diesel or something like that. And use a LOT of diesel fuel additive, a good one like Amalgamated, mixed at 2-3x the normal amount.