anybody heard of this fuel called black diesel. What it is, is diesel fuel that is mixed about 50/50 with used engine oil. ive ran 3 tanks of this 50/50 mix through my truck with out any problems just wondering if anybody else is doing it.

 

It's been done. Here's a popular thread:

https://www.dieseltruckresource.com/...&highlight=wmo

 

I wouldn't do it myself. Motor oil has additives to KEEP it from burning and it has byproducts of engine wear....neither one, I would think is good for injectors or cylinders. Newer trucks with fancy mavericky exhaust scubbers might not like what comes oput either.
I had some 2cycle oil but not 50/50 amounts.