I used to run a Ssangyong Musso, 2.9 merc diesel, on rapeseed oil, sunflower, recycled chippe oil,..i did a 50/50 mix, and it never broke down, it was cheaper then as the cost of veggie oil in the supermarkets was only 3lt for 80p this was in 2004, but like everything else the makers soon cottoned on to thje fact that it was being used to fill tanks, now the price is the same as diesel, but,in bulk buying it can cost 65/70p per lt,
I now run a 1.6td Berlingo Multispace,2011 model and have on occasion put veggie oil in this, and it runs, mind you, it does smell like a chippe van running down the road