I have been using Used Cooking Oil as my fuel of choice since September 2000.
That car was a Mazda Capella 2.0 litre diesel. I can discuss that conversion in detail at another time. If anyone wants to read of it, it was the basis for a paper presented to the Waste & Recycle Conference in Perth in Nov 2001. It is online at www.shortcircuit.com.au

This is my Third "Fatmobile"

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Details:
"Cold filtered" oil - liquid at lowest temperatures in which the vehicle is stored. No need to heat the fuel tank.
Garden hose as fuel line - $3.99 for 10 metres, including tap and director fittings. This was cable tied to stock diesel fuel line fromthe engine bay to the rear axle.

Fuel heater - a plumber made this up for $150. It has 2 coils of 5/16" copper in a water jacket, connected to the engine coolant system.

Change over valve - Pollak 6 port valve. This has 2 changeover valves, which allow me to select the fuel source and direct the return line to the appropriate location. Available from Brown & Gibson in Melbourne at approx. $75 each.
Fuel pressure gauge - excellent for diagnosing fuel starvation / filter clogging issues - #39.95 at Repco on special around 3 years ago.

Fuel filter - I obtained a second hand CAV fuel filter which has a glass sediment and water bowl at the bottom. $35.00 plus $10.00 for new element.

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Fuel tanks:
As this was the "economy conversion", with no heating of the fuel tanks, I decided to use 2*20 litre translucent HDPE chemical drums (Cubies) which had contained detergent or floor cleaner.

By using a long fuel line from the pick-up in these tanks to the fuel line in the car, It allows "out of car" refuelling.
NOTE: I am investigating the installation of a steel fuel tank, occupying the same location in the boot, but with approx 60 litre capacity, coolant heating and fuel supply and return line connections. A tank drain valve is part of this plan, to permit draining of any water from the tank.


Coolant is sourced from the heater coolant lines, here as the hot coolant comes from the head. I made sure that the Tee did not obstruct the oil filter when servicing.



Coolant is returned to the engine at the water pump.
NOTE: the above photos are from a different vehicle, but the connections are the same in this vehicle.


Attachments -
The connections to the coolant system:

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Here are some photos of how the fuel line for the Used Cooking Oil is run under the vehicle.

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UCO Fuel line under the front of the vehicle:

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UCO Fuel line adapted to Nitrile Rubber fuel line. UCO Fuel pump (Holley Blue) seen here too.

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UCO Fuel heater, seen above during assembly, shown here installed in the Fatmobile.

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Fuel selection valve - Pollak 6 port valve is actually 2 changeover valves on a common motor drive.

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You have seen the parts of my conversion, here is the diagram of how it ties to the fuel system.

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Driving the Fatmobile.

I start the engine and drive the car as usual.

When the temperature gauge rises to 80°C, I operate the switch to change over to UCO. The Pollak valve changes to UCO and I continue driving with no difference in power or engine response.

If I wish to stop for a few minutes, I just stop the car & shut off the engine.
I come back to the car, start the car as normal and drive off.
When I plan to stop for a while and the engine is likely to cool down, I operate the changeover switch to select the main fuel tank around 2 - 5 km in advance of the stop.
When I arrive at the stop, I shutdown as usual.

Other than the changeover switch operation, there is no difference in operation of the vehicle.

FAQ.
Q1. What happens if I forget to change back to diesel before shutdown and the engine cools down?
A. With the OM617 diesel in my car, this is not an issue, it will start with a little more cranking than normal, but in the Mazda, I needed to pour boiling water over the injectors and IP, before it would start up again. With high Melting Point oils, attempting to start on solid oils may cause IP damage in some vehicles.

Q2. Why am I heating the UCO?
A. Vegetable oils are much more viscous than diesel. To allow the IP to pump the UCO and the injectors to spray like they do on diesel, we can either chemically modify the oil (make biodiesel) or heat the oil to reduce its viscosity. I use heat to lower the viscosity.

Q3. Is there any tax or excise payable on UCO?
A. No, vegetable oils and animal fats as diesel fuels are specifically not included under the Excise act which was passed last year.

Q4. What did this conversion cost?
A. THe conversion costs I inccurred were only parts costs. I performed all labour and design functions.
Fuel tanks - nil - used 20L chemical drums were free.
Fuel line $3.99 for 18 metres, complete with fittings and nozzle (not used)
Fuel pump $100.00 + $20 freight for a used Holley Blue fuel pump
Fuel heater $150 fabricated by a friend who is a plumber (note 2 fuel lines in the heater)
Fuel selection valve $75.00 plus $2.50 for switch
Coolant Hoses, Tees, Fuel lines, hose adaptors, hose clamps etc - say $150

TOTAL less than $500