Biodiesel
Here is my experience of 3 years using biodiesel: burns good. Used veg oil is easy to come by, at least it is here in eastern Ontario near Ottawa. I collect from chip trucks in a small town and take to a dude in the city (Facebook Ottawa Biofuel). He processes it with a small scale commercial processor. Occasionally there is some sediment on the bottom of the jugs when I get it from him. I just try to pour the clean stuff off the top and leave the cruddy stuff in the bottom. I usually run 40-70% biodiesel and the rest is the stuff that is destroying our planet's climate. Occasionally I'll burn B100. I've changed my fuel filter 3 or 4 times and put on 40,000km. When the fuel filter is starting to get clogged, you can tell. It will hesitate under heavy throttle. Ive never had it clog altogether to the point the truck wouldnt run. When it hits -25C I try not to have very much in the tank. But even when its B20 I havent had any issues. The fuel gets through, it just wont respond when you step on it.
THe truck is an '02 with 140km. Injectors never been done. The truck smoked on start and idle but now it doesnt smoke AT ALL. It took a few years, and got less and less to the point now that it doesnt smoke... ever. This is what big oil doesnt want you to know. Its better for your engine.
I havent noticed any loss of power.
The fuel is about the same price at what you'll pay at the pumps, but the price will not go up on a long wknd. I pay less than the price at the pumps. I would rather change my fuel filter slightly more often but extend the life of the injectors, fuel pump, and upper cylinder since they are cleaned and lubricated by biodiesel.
Iis a totally non-toxic fuel. I use it to clean my hands of grease. It has very little odour as a liquid. However when you burn it you might give people behind you a craving for some fries.
Give it a try, your Duramax will thank you.