There are a few old threads around but rather than resurrecting one I thought I'[d give it another go - by way of an update.

Anybody chancing their arm with veg oil?

Currently, diesel is £1.20 per litre & I can buy new cooking oil for 80p/litre.
I've got about 50 litres of waste veg oil which I plan to filter to less than 5 microns - free fuel but I'll still be mixing it.
2006 doblo 1.9jtd
At the moment I'm running my doblo on a summer mix - now 2 gallons veg to 8 diesel by way of filling the tank, driving 90 miles then adding the veg (as I average 45mpg & tend to fill up with around 10 gallons). Spring and autumn I run at 1 gallon veg to 9 diesel and when the temps really dropped over winter I kept it neat diesel.
The only problem I have noticed is that on some colder mornings, tickover can be a tad 'lumpy' but nowhere near as lumpy as my old diesel was running on just diesel!
Aside from that, I'm still averaging 45mpg and the old crate can still motor when I need it to. Still happy to sit all day at 70mph. as well.

Really! So if I chucked a few bottles of sunflower oil in the tank I could still motor, in summer at least?

I am surprised, because the JTD is supposed to be quite advanced and has a very carefully engineered injection system.

Should I take myself down to Lidl and fill up?

you are supposed to use used oil as the boiling & cooling thins the oil & makes it more burnable. on cold mornings the oil thickens & when left over night separates in the tank. you need a heater to warm & then thin the oil mix but it can then thicken in the filter (pain in the a**e). i tried it years ago in a synergie hdi & found these tips useful
:slayer::bang:

Ulpian said:

Really! So if I chucked a few bottles of sunflower oil in the tank I could still motor, in summer at least?

I am surprised, because the JTD is supposed to be quite advanced and has a very carefully engineered injection system.

Should I take myself down to Lidl and fill up?

Click to expand...

Obviously I was extremely cautious at first. Most stations now deliver a 5% mix as standard from their diesel tanks (so I was told by Tesco - part of a government initiative on cutting something or other blah blah blah) so I started by adding 1 litre of veg at each fill of 45 litres. As time went by and I noticed no adverse effects I got braver.

briangoo said:

you are supposed to use used oil as the boiling & cooling thins the oil & makes it more burnable. on cold mornings the oil thickens & when left over night separates in the tank. you need a heater to warm & then thin the oil mix but it can then thicken in the filter (pain in the a**e). i tried it years ago in a synergie hdi & found these tips useful
:slayer::bang:

Click to expand...

Even used oil is still a tad viscous but I read somewhere about adding white spirit to 'let it down'. I then read on another forum that if plod pulled you and dipped your tank, they could tell if there was white spirit in there (don't ask me how, this was what I read) and not all taxes had been paid on it so you'd be stung for the tankful. They felt it was better to thin the veg oil with 3% petrol - all fuel taxes paid & allowed 2500 litres veg oil before subject to tax.
Only read this recently though so not had a chance to do it yet.

BTW, I figure that by running the tank down & filling with 10 gallons, it'll dilute what's left of the veg oil further meaning a 'neater' diesel mix is running through the system for at least 90 miles before I add the veg.