There's absolutely nothing to worry about running veg oil through your engine. I'd suggest starting at a little less than 50/50 first though, just to see what you think Maybe 30/70.
It wont really block up your injectors or any other part of your engine unless it meets water. Air doesn't have that great an effect on it. To see the effect, pour a bottle of morrisons, or asdas veg oil (not crisp n dry, too expensive) into your tank but leave a little drop in the bottle. Swill the bottle out with hot or cold water and it'll go a little cloudy and stick hard to the sides of the bottle. If you're still not satisfied blend a little diesel and some vegetable oil in the bottle, screw the lid on, run it under the hot then cold tap and leave it for a day or two. It just looks like ordinary fuel, no solids.
As long as it is mixed with diesel and there's no water in the system, there's nothing to worry about. You only need a heater kit to heat the oil up and thin it down a little if you're running on it 100% because it is thicker than diesel, and it will put a little extra strain on the pistons because it's harder to compress than standard diesel. Once your engine has warmed up, the oil doesn't need to be heated because the heat from your engine heats it up and thins it out enough to compress to its optimum potential its self.
It's good stuff. Just make sure that you change your fuel filter after one thousand miles (no less, it wont have collected anything) because veg oil is good at cleaning any crap out of your fuel tank and fuel lines leading up to the filter.
-Pos
