JackG has a very good point. That is what I've been doing, buying a beater, driving it on WVO and then parting it. My first 300SD I drove 30K miles. about 25 of those were on BD and WVO/RUG. Had injector nailing a couple times, but it cleared up all by itself. Love these self-healing Benz's.
I would like to think that if I burned WVO in the summer and then switched over to diesel in the winter, that the WVO fuel use woulf clean the deposits from the dino fuel use and the dino fuel use would clean what the WVO left off. Would be nice wouldn't it.
Either way, BD or heated WVO you're gonna invest several hundred EXTRA dollars in parts. Either a processor and it's pumps, titration equipment, safety equipment,,,, or in a 2-tank system - a second tank (maybe) plumbing, Hose in a hose, switches, pump/valve,,,
Simply using WVO/RUG the only investment you need is a sock filter and a couple of buckets.
See my ebay guide on WVO and diesels:
http://reviews.ebay.com/Burning-WVO-Waste-Vegetable-Oil-in-Diesel-Vehicles-benz_W0QQugidZ10000000001239706
and PLEASE check the yes button.
Thanks