If this will help, I read recently in a 1960 Mercedes diesel manual that it is OK to thin out mixes of summer diesel and other oils with 10% gasoline by volume. At the time, Mercedes warned users NOT to mix premium gas with the diesel fuel because the premium gasoline contained a vanadium additive. I looked up vanadium and it is an element and also a catalyst that causes other chemical reactions. Regular leaded gas was ok, just not the premium.
It appears that all except the newest Mercedes fuel injection (after 2005) pumps were stout enough to handle this mix. The biggest issue was viscosity, or thickness, or runnyness or whatever you want to call it. If the mix is too thick, it stalls out and can damage the pump. This is why many vegetable oil vehicles have a fuel heater.
However, I have discovered that different oils each have a rating for viscosity.
Normal diesel has a rating of 2.5 to 3.5 whatevers, and that you can look on the internet and find the viscosity of every kind of oil.
So once you know this, a little arithmetic before you mix and you are ok!
I am also ready soon to start purifying my waste motor oil and other waste oil. At auction I bought two Air Force portable biodiesel makers, each one is on a wheeled cabinet that is 5' x 5 ' 5 ' and do about 5 gallons at a time, using 110 VAC.
Still getting to understand how this contraption works, then I will start making this stuff and report back.
I have also seen a company called Schroeder that makes a pump that filters up to 16 gallons per minute all the way down to 6 microns, or 6/1,000,000 of an inch! Also runs on 110 VAC and has paper filters that do about 18,000 gallons before they need replacement. The filters are 20.00 a piece and you need two per filter change, but if you get the oil for free, it's a small price to pay.
Right now, I've got maybe 100 gallons so I will wait and set up some 55 gallon drums when the weather gets warmer. I'll filter 55 gallons at a time, then run it through the biodiesel lab and see what the oil looks like.
I have to think I can get it to look pretty clear if it gets two runs through the filters.
A guy I know at a college says you can make a measuring device to get a pretty good idea of viscosity if you can find some very tiny drills and a piece of plastic angle that is 2" x 2" 12" the drills and some glass jars or measuring cups.
Time to use Grandma's old Pyrex glass measuring cup for something besides pancake batter!