SVO is thick stuff. You have to have a two tank system. The WVO/SVO tank is heated to 140F or so, and the other tank is filled with diesel to start and purge to stop.

If you fail to purge the lines of SVO before shutdown, you will have a hard time starting in cooler temps, and other problems as well.

Biodiesel is SVO/WVO with the fats removed from it, yielding a less viscous product.

 

Biodiesel is essentially vegetable oil that has been processed to have the gylcerin removed. The glycerin is what makes the vegetable oil have the higher viscocity.

SVO (Straight Vegetable Oil) is too thick to go through all but the lowliest diesel engines when it is at room temperature. That's why you see a lot of talk about 'heating SVO/WVO', and read about systems for doing that using various methods of electrical heating or using heat exchangers with engine coolant.

Biodiesel (SVO with the glycerin removed) can be run straight in virtually any diesel engine without modification - it is thin enough (low viscosity) and can run through the injectors and pumps without problems associated with being too thick.

Biodiesel has some problems in that it has a high solvent value, so it will remove any buildups from petroleum diesel usage and possibly clog your fuel filter. That's why you should start with B5, then go to B20, etc. and work your way up when you switch to biodiesel, as you want to slowly clean your system, and change filters along the way. After 3-5 tankfuls, you can go to B100.

Also, biodiesel is rough on natural rubber (again because of the high solvent value), so if you have any natural rubber in the fuel system (e.g. seals, fuel lines, etc.) they will be degraded by the biodiesel. In most vehicles built in the late 80s and 90s, this is NOT a problem.

I hope this helps you a little bit.

Sincerely,

Rob

 

So you could dump a gallon of crisco light into the tank as a lube?

 

Maybe. In summer months, it would be probably be fine. In cooler times, maybe not a good idea to just "dump it in". Reason being is the oil and the diesel may not mix well in that mode, and you would run the risk of sucking in a slug of almost pure oil. In the summer, it likely wouldn't be a problem, but in winter it may be too viscous for the fuel system to handle. If you want to use it as a lube, I would premix it with a few gallons of diesel in a 5 gallon can, then add to the fuel tank.

To elaborate on Rob's comments, the making of biodiesel isn't quite as simple as removal of the glycerin. Oil is made up mostly (new svo is ~95%) of triglycerides, which are molecules with 3 fatty acids attached to a glycerol backbone. To make biodiesel, those fatty acids are cleaved from the backbone and a carbon group is attached to the end of the fatty acid. Most biodiesel is made with methanol, so a methyl group is attached to the acid to make a methyl ester. The remaining glycerol backbone reacts to form glycerin, which is insoluble in the ester, thus settles out and is removed from the system.