Ok, i've heard people say 'don't do it' before, but a guy i know is taking waste oil and sending it through many filters (i'd say 7), and then heating the oil up, mixing it with diesel, and sending it through a centrifuge... he ran it in an old cummins for a while and nothing went wrong, besides the smell of burning oil.
he runs it in the backhoe, and now his truck...
what's y'alls take on this
now i dont want any bashing, just opinions, remember it isn't me doign this
It is very risky to run waste motor oil.
Diluting it will reduce but not eliminate the risk.
Waste motor oil has a considerable load of submicron (smaller than one micron) particles in suspension. It is these particles that give used oil its black color. If you can restore the oil to its original color, by filtration, you can assume you have removed all of the particulate cantaminates; however, you have not addressed the chemical by products of combustion, most of which are acidic in nature and can attack metal parts in the fuel system.
The more sophisticated your diesel engine is the more likely the acids and submicron particles are to do damage, the old cummins and possibly the backhoe may tolerate the contaminated fuel while his truck, if one of the newer engines, most likely won't. Damage may take time to accumulate to the point of being a problem but at that point may be irreversible.
I will not run WMO in any concentration in my truck. I am not willing to gamble my $10,000 engine to save a few bucks on fuel.