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3562 Days
of trouble-free motoring on veg oil since converting on 18th June 2008

WVO Rough Filtering / Settling Process

Beyond a doubt, the greenest option when it comes to running on Veg Oil is to use Waste Vegetable Oil (WVO). Thankfully this is also the most affordable running option as well.

There are a variety of ways of filtering WVO, but my preferred method is settling. Essentially this means that rather than using a variety of pumps, valves and filters to force the impurities out of the WVO, we allow gravity and time to do all the work for us.

Learn about Settling - my video on YouTubeSettling

Settling is fundamental to most of my filtering techniques described in this site. I made a YouTube Video on the subject that you may find helpful. To view it, click here.

Waste Veg Oil is invariably contains all manner of debris, like batter, crumbs, chips. etc, as well as fats and water. It's essential that ALL of these impurities are removed from the WVO before its used within your vehicle. Failure to do this will result in expensive motor repairs!

We can does this easily by employing a technique called "settling." In essence it simply means leaving the oil to stand still, unagitated, for a length time. Gravity slowly and gently pulls the larger impurities within WVO towards the bottom of the container, allowing the cleaner oil to float to the top. Thus water, fats, crumbs, batter, etc, will all fall to the very bottom of the container if the oil is allowed to rest long enough. My YouTube Video on the subject may make all this a little clearer.

I use a two stage process to clean my WVO. Firstly I rough filter / settle my WVO, then Secondly I fine filter it down to 1 micron.

My WVO Filtering Set Up - Stage One - The Settling Tank

Filtering WVO - Creating and using a Settling Tank

Before I discuss further my Settling Tank, please note that I've been refining my methods for a number of years now. Whilst the below is still valid and useful, you may find it advantageous to watch my YouTube Video on the subject first.

In the video (which you can see here) I discuss the various methods I describe later on but speak with far more experience and give helpful tips that might not yet be within these pages. So please, save yourself some time and view my video first. Then if you need more details, you'll find these here.


Below you'll see a sketch of my Settling Tank (click here for full details about my filter system). The tank is a small shipping container purchased from eBay that has already been used to transport foodstuffs around the globe. I say small, it's actually a 220 litre barrel, but that's small when you think of many shipping containers...

WVO Filtering Settling Tank Setup

The WVO Filtering Process

If you pick up your WVO in Cubies (those squarish plastic containers) then you really should use the Cubie Method for pre-filtering your oil. I have a YouTube Video on this subject that you may find helpful.

If you're not lucky enough to be able to take advantage of this terrific time-saver, then you'll need to pour out you oil through a filter mesh of sorts to serparate most of the debris. I used to advocate Strainers / Sieves for this purpose, but I found them very troublesome - they clogged much too quickly! I'd recommend using fashioning a cone-shaped strainer - you can see more about these in this YouTube Video.

And so, on to the process

  • 1 - Stockpile your WVO until you have enough to fill your barrel.
  • 2 - Rough filter the oil into the barrel using a cone-shaped sieve of approx 200 microns.
  • 3 - Discard any sludge that fouls the sieve
  • 4 - Seal the barrel and wait 4 weeks
  • 5 - After 4 weeks, drain the settled oil, but NOT from the bottom, rather from three-quarters of the way down the barrel. 6 - Similarly do not empty from the top of the barrel, but rather from at least 1 inch below the surface.
  • 7 - Fine filter to at least 5 micron (I prefer 1 micron) and use.
WVO Filtering Sieves
WVO Filtering Sieves Stacked
I used to use flat-bottomed strainers like those pictured above, but I found these quickly clogged. I converted mine to cone-shaped strainers. This YouTube Video will tell you more.
WVO Filtering / Settling - Click to enlarge
Click to enlarge

(1) I stockpile my WVO until I've got enough to add to my Settling tank.

(2) When ready, "rough filter" by pouring the oil through a cone-shaped sieve into the barrel. Do this as slowly as possible as you'll probably find the closer you get to the bottom of your container, the nastier your waste oil becomes - more debris, fats, etc. If you can avoid pouring this ini, then do so! There's little benefit in trying to filter such gunk. I used to use flat-bottomed strainers like those shown in these images, but they clogged too quickly. If you have them, try converting them into cone-shaped strainers instead. This cYouTube Video will give you a better idea what I'm talking about.

(3) Depending on the WVO sourced, I can lose up to 30% of the volume as it's unusable fats and debris. Don't bother trying to filter fats - it'll never happen!

(4) Commonly most folk leave their WVO to settle for 2 weeks. Personally I prefer to leave mine 4 weeks (better safe than sorry). During this time gravity pulls the heavier content of the WVO to the bottom of the barrel.

(5) Consequently you NEVER want to empty your barrel from the bottom as that's where all the sludge is. Instead draw off around three-quarters the way down your barrel where the oil is cleaner.

(6) Not all impurities sink to the bottom, some float on the surface. Consequently you do NOT want to use the top WVO either, but ideally want to remove oil from around a inch or so below the surface.

This completes the rough filtering stage

After you've allowed the WVO time to settle, you can draw of oil for (7) fine filtering. Within this website I've described this process as Stage 2 - Fine Filtering and to read more about that, just follow the link here.


WVO Filter Design - Click to enlargeClick to enlargeClick to enlarge


Click to enlargeClick to enlargeClick to enlarge



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