I wouldn't recommend burning crankcase oil in a 1 to 1 or even a 2 to 1 scenario. I had a Mercedes Diesel strictly for testing concoctions of fuel. Veggy fuel, Bio fuel and even the Crankcase Oil fuel. What I found was the Veggy is OK but tends to plug up the injectors. Good Bio-Fuel works great. Rapeseed is a Mustard family plant and will make some people breakout in rash. Crankcase oil, I got the filters together like there little mystery system is setup. Mixed the oil in small batches trying to get to their magical "Runs Great at 2 to 1 ratio!" First thing I noticed is that it ran but progressively got harder starting. Cleaning the injectors helped that. Running more and more oil then started plugging up the engine filters. Started changing them more often. The performance of the engine started declining more and more over a period of a few months while at the same time the crankcase blowby kept increasing. Finally I tore into the situation and found that carbon build up was the problem especially in the mufflers. We scrapped the project and started burning this stuff in a waste oil heater in the shop. Which verified the carbon buildup because it collected in an elbow within 3 weeks and back fed fumes into the shop. Upon disassembly the carbon was actually collecting in the pipes as a furry shaped string that fluttered in the heat. I talked this over with various Engineers and came up with the facts that crankcase oil isn't just a petroleum product anymore but a complex mixture of additives in a petroleum base.
Our final concern is the burning of heavy metals and a few noxious chemicals.

I have 6 tow trucks and 6 tractors. They all love biodiesel. More horsepower, more mileage, but it is caustic. It cleans them out like crazy.
It's more expensive here or we'd run it all the time.
Hopefully we'll be making it before winter.

From the last two posts it sound like you could alternate fill ups between biodiesel and WCO!
One tankfull would dirty the system, the next would scrub it, it would be a wash!

CS