Have done quite a bit of reading on the subject, i have not run SVO in a diesel so for what it's worth. Heating SVO is to thin the viscosity of the oil so that it is about as thin as diesel fuel. And from what i have read and the people that i have talked to that have done it older engine designs are much more tolerant of thicker fuel. So if you are in a warm climate and have an old diesel you might be ok with out heating the fuel. If your engine is not tolerant of thick fuel you will damage the injectors $$ or the injector pump $$$$.

There is more information out there but here is a place to start,

http://journeytoforever.org/biofuel_library.html