Tuesday, 7 December 2010

Running on vegetable oil in cold weather

In cold temperatures, as we have at the moment, crystals can form in the vegetable oil, making it impossible to pump through fuel lines and filters. I sometimes leave a little pot of vegetable oil in the car, so I can see what it looks like when I get in the car in the morning.

The crystals form as the temperature drops at night, but they don't disappear until the temperature rises a few degrees, which can leave you waiting for a warm day before you can use the car.

The trick is to stop the crystals forming in the first place. I do this using a fuel additive called Coldflow 350. I add about 25ml per 10 litres of vegetable oil, and it keeps the fuel flowing.

Even with the additive, the fuel is quite thick, so I also have some electric heating to warm the fuel up on its route from tank to injectors. That way, when it reaches the fuel injectors, it is thin enough to spray into a mist and ignite under pressure.