I run a mixture of 50/50 diesel/wmo whenever I can get my hands on the oil. I think I found a pretty good supplier of clean used oil today. My truck is an 01 7.3l, and I see no more smoke tunning th used oil, it does run quieter then usual with it for sure. The mileage for me is the same as with diesel, it just cost a Shik load less to fill my truck doing this. If you calc out what your savings are using the wmo you could spend alot on repairs if you needed to in the future with all the money you will save. I just can't believe I used to recycle this stuff, instead of putting it in my tank. My plan is to start using it all the time in my truck, and I will start mixing it about 80% oil and 20% diesel once my supply gets more steady on the oil. There are alot of guys out there doing this, some running straight WMO, and some running 90/10. Calculate the savings yourself, it is like getting diesel for a dollar a gallon again with the free oil running at 80/20. My fuel bill runs a grand a month on straight diesel just for one truck. I have other vehicles I fill also, so this is alot like a free lunch to me. I will never go back to straight diesel again, makes no sense to me to run it in your engine at these prices!!!!! PS don't tell the locals innyour area, they will think you are crazy first, and then try and swoop in on your free oil once they see it works just fine. Diesel engines are very forgiving, and Rudolph Diesel did invent this engine so farmers could grow there own fuel to supply there engines on the farm, makes complete sense to me to never run pure EXPENSIVE diesel ever again.