I know I am not a chemist, however, I do have an engineering degree. I do know enough chemistry to know that waste veggie oil is nothing like BIO diesel. Biodiesel is called "bio" simply because it originates from veggie oil. It goes through a CHEMICAL change (which includes and extreme HIGH temperature heating with additives like methanol and lye, dry washing and a couple of filtering stages to rid the fluid of any glycerin particles before it is fit to use) once it goes through the chemical change it literally become diesel fuel... it is no longer veggie oil. It has a much LOWER sulfur content but a much HIGHER oxygen content and that is why it cleans out your fuel system so well, and requires filter changes when you switch over. Certain vehicles may be able to run straight veggie oil and it if works, great. Keep in mind it is a RISK...just be careful.

 

There is a drain plug on the fuel tank. Just have a suitable container available that will hold the amount of fuel you have in the tank. Drain and then refill with fresh diesel. You may need to prime filters and the IP. Not quite the same a s running out of fuel and everything is dry. I would try start it after filling tank and if it stops or won't start then prime the filters and the IP.

 

+1, and I really like that word.