Any one see Top Gear last Sunday? Their Beemer 330d died when their Rapeseed bio-diesel "ate" the fuel pump seals ...
rather, it was because the fuel had too much methanol in it.
Methanol is used in the process of making this fuel and in their case the fuel contained too much of it.
methanol is highly corrosive, most pumps (even those designed to pump some methanol) can typically handle up to 50% methanol, beyond this you are looking at specialist pumps.
A fuel pump (seals) are not realy designed to be pumping methanol at all, that is what caused it to fail.
Veggie oil alone should not damage pump seals at all, its just too thick (viscosity) to pump efficiantly.
Its the Bio diesel (re used old chip pan oil) that uses methanol in its process thats the real bad stuff.
There is a company here in Derby that sells this rubbish, most of the cars/taxis that use it have turbo and other problems.
What's more, its 80p per litre, hardly worth the saving?