Sustainable livingWaste Veggie Oil

Veggie oil conversion – the installation

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WVO installation day

Chris continues writing the story of of conversion of our bus from dirty diesel to waste vegetable oil. Enjoy!

I am an achiever. I love getting things done and crossing them off my long lists. We’ve had a daunting bus jobs list these weeks since returning from Nepal and the largest, most complex and most interesting job has been the veggie oil conversion. Read the backstory here.

My mind had been steadily planning the conversion for months and finally the time was right to drill and mount and plumb and wire. The stage was set – our friend’s farm in Pinjarra, Western Australia; a relatively flat open field, perfect fine weather forecast with light winds for 5 days and few other distractions.

Here’s how the installation went

DAY 1: mount the heat exchanger (HX) and position coolant lines to HX

DAY 2: mount the supply and return valves, run and fit all fuel lines, mount veggie pump and pre-pump filter. (Tip – use Loctite aviation No 3 sealant)

WVO valves and HX

DAY 3: run and join all wire cables and relays, prime veggie system with diesel and “test run” the veggie system with diesel

DAY 4: remount HX to be well out of the way the steering arm (and spend the rest of the day feeding chickens and cows)

I probably didn’t have to remount the HX but I woke early on day 4 to the image of a crushed HX and coolant leaking everywhere and the engine overheating. You know exactly what I’m talking about. And it seemed easier to reposition the HX than convince myself it would never be hit.

DAY 5: collect 160L of used veggie oil from Pinjarra Fish and Chips – thanks Warren and Skye!

Collecting WVO in Pinjarra

DAY 6: clean 160L of veggie oil through our WVO Design centrifuge, introduce clean veggie oil and “test run” the veggie system on real veggie oil

Let me tell you more about the centrifuge

Oil cleans better when it spins fast and spinning oil cleans better when its hot. What we’re aiming to remove from the used fish and chip oil are fine suspended solids, fat and carbonaceous products and water. We ran our first oil through at maximum flow (about 70L/hr) and temperature (110oC) and it seemed to clean up well as the “clean oil” was very clear and the centrifuge bowl contained plenty of black soot and particles. We ran the “clean oil” through a second time and found that we removed even more black – so we decided to reduce the flow rate to 45L/hr by simply adjusting our valve in the gravity feed line.

Cleaned veggie oil

Four hours later – we had cleaned 160L, filled our veggie tank and placed 40L spare in the boot. A good morning’s work!

We removed about 2 litres of foul oil from the centrifuge and here are the solids collected in the centrifuge bowl after spinning our first 160L.

Black solids in centrifuge bowl


The final trick with the installation was setting the “flush time” – when changing from veggie oil to diesel you want a delay in the return valve to avoid sending veggie oil to the diesel tank. Flushing the injector lines and filter typically takes about 20 to 200 seconds depending on the size of your injectors and filters. During these test we determined the flushing time to be about 40 seconds. We then run the bus on diesel for a further 3 to 5 minutes to ensure no oil left in the fine injectors.

Successful test drive on the highway

On DAY 7 we planned our maiden voyage (test drive) on veggie oil by driving 85km from Pinjarra to Perth. We woke to see our road out of the farm was flooded and we measured 59mm rain had fallen over night – perhaps this wasn’t going to be the best day for our test drive.

The rain subsided and an hour after breakfast we attempted to drive out through water and mud and we made it to the highway! We attached our little Suzuki on the back, set the ATG WVO controller to auto and it worked perfectly; reached temperature, switched from diesel to Veg and there was no interruption to driving or change of performance. I stopped a couple of times to crawl around to see the fuel lines and listen for strange noises (as you do) and everything seemed perfect.

Final step was to check the flushing time again as we detached the Suzuki and we then ran the last 5 minutes on diesel to ensure no veggie oil in the injectors.

We drove our bus on veggie oil!! We officially have a greasebus!! And we have enough veggie oil to get us the 600km to Geraldton and beyond!

Here’s the story in video.



  1. Wow, you did it! Well done. So after all that, does the oil still smell of fish and chips? Is the WVO exhaust smoke as dirty as diesel smoke? And how long, from collection of the waste vegie oil to putting the cleaned stuff into the tank, does it take?

    1. Hi Michelle, the cleaned oil doesn’t smell but the WVO exhaust bears a slight reminder of fish & chips. The exhaust is different to diesel exhaust – similar CO2 but fewer other particulates.
      We processed 160L of WVO in half a day – I think this will be fairly typical as the centrifuge treats 45L/hour.

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