With the ever increasing fuel prices, it starts to make sense to use a mix of diesel/SVO, as you can buy it cheaper per liter than diesel fuel.

What is a safe diesel/SVO ratio to use? I don't have to worry about the fuel freezing, as the temp is never below 20?C at night, and ~35?C during the day.

In my understanding, freezing of the SVO is not the real problem but gelling at lower temperatures is an issue. It has to be heated to maintain a liquid consistency. I'm not really too sure how it works with mixing fuels, but that is something to keep in mind as your fuel/SVO ratio goes up.

in know here in the united states the kit that i run in my 2001 powerstroke has a second tank that is heated in the bed that keeps the wvo OR svo at a constant 190 degrees this is the optimal running temperature this is achieved by using electric heaters in the tank or by using engine coolant to keep the oil at the temperatures needed to allow it to flow threw the fuel lines and then into the injectors with out clogging them also vegetable oil has a higher BTU rating than diesel to start with it is just the problem of keeping the oil in a liquid state but that is easy to remedy with heaters if you need any more info on this let me know

ALSO SVO = STRAIGHT VEGETABLE OIL WVO = WASTE VEGTABLE OIL

AS SUCH THERE IS NO DIESEL MIXED IN WITH IT YOU USE DIESEL TO START AND HEAT UP ENGINE THEN SWITCH TO SVO OR WVO AND 10-15 MIN BEFORE SHUT DOWN SWITCH BACK TO DIESEL

check out golden fuel systems good site plenty of info

Right. I'm working on my own dual-tank system to start using WVO.

In response to your first question, I have found a couple of sources that say you can use up to 20% veg oil in your tank without having to worry about all the mods that the heating process entails.