My daughters response to my costings for a trip out in the van based on 20miles to the gallon at £2 a litre; ' Yeah we'll figure out how to use chip fat'.
Polite thoughts please
Polite thoughts ..... "when did you get a mobile chip van?" Well, that is the comments I used to get when I ran my VW T4 on veg oil. DIdn't care as any smells were behind me
As said, depends on vehicle.
An engine with a Common Rail engine (so anything reasonably modern) would be a big no-no.
My 2000/W Reg VW T4 ran perfectly on Veg Oil without any adjustment to anything. I would buy cases of 100% Pure Rapeseed Oil from Bookers C&C and fill up.
SVO vs WVO (you may have seen those terms?). SVO = Standard (i.e. NEW) Vegetable Oil. WVO = Waste (e.g. Chip Fat) Vegetable Oil. WVO MUST be filtered before use very well. Scrappings are a lot bigger than a fuel hose! Some people filter using pairs of old tights and the like. I just stuck to SVO.
Seasons. No worries in the Summer. In the Winter, Veg oil thickens up so much it won't flow. I used to use 100% SVO in summer, 50/50 mix Veg Oil and Diesel spring and autumn, 100% Diesel in Winter. I have a neighbour who used veg oil all year round... his pickup had to be collected on a low loader to the pipes cleaned out. I bet his fuel savings got wiped out! you can fit heaters as mentioned, but starting to get into extra complexities and costs - is the fuel saving enough to warrant it?
Rubber! depending on the fuel pump fitted it, the seals could disintegrate with Veg Oil. with the T4s, there were two official brands of pump, Bosch and (I think) Lucas. Bosch was fine, Lucas was a big no-no. I also had to replace the fuel filter on a more frequent basis (veg oil is a much cleaner fuel than diesel and tends to actually clean the fuel tank and dislodge years old gunk that then gets caught in the filter)
End of the day, if I still had a vehicle (such as that T4) that would run on Veg oil, I would absolutely be doing so