View Full Version : Wanting to set up a filtering system for blending

14th October 2012, 02:59 PM
I'm just getting into the wvo scene, got an '86 F250 and work at a restaurant that is giving me all of their used oil. I've decided that for now I'm going to be blending, using the blend in one tank and then switching to the other one to purge with diesel, in case it gets too cold this winter.

Thinking about how to go about filtering, I don't have a whole lot of money so would like to keep it simple and cheap, probably not going to get any of the inline setups. Was thinking about bag filters, how many would I need and are there any plans for a contained setup that uses bag filters, like 5 gallon buckets stacked on top of eachother or something similar?

Also I'm glad I found this forum, will probably be spending a lot of time on here.


Tony From West Oz
14th October 2012, 10:31 PM
Welcome to the forum, there is plenty of information here for you to find. Use Google to search within this site (add "Site:.bioduelsforum.com" to the search line in Google) so that your search is confined here.

I have been filtering used cooking oil for my WVO cars for around 12 years now and have found that bag filters are the simplest filtering method. Use gravity to force the oil thru the filter, fill the bag up morning and night and the oil will continue to flow.
If your oil has some tallow or palm oil (AKA Fats) in it, you will find the filtering will slow down as the fats build p in the filter bag. You are concerned about low temperature operation, so it is best to filter out the fats so that they do not get into the fuel tank.

Search for "filter liner" to see how I deal with the fats in my filters.
Search for "upflow settling" to see how some other members here separate the fats from the oil.

Google is your friend on this forum.

Best wishes,

15th October 2012, 09:57 AM
I did a search for filter liner, that's something I hadn't read about yet. It sounds like a reusable cloth shopping bag is commonly used. Not sure about the quality of my oil, it's from a Chinese American restaurant.. I let it settle in a barrel and the top layer usually ends up looking pretty clean.

I've looked into it but can't figure out a couple of things, how many bags total should I filter the oil through? Can I just stack the bags so that the oil progressively goes through each one?

Thanks for the help Tony.


Tony From West Oz
15th October 2012, 09:55 PM
If you are straining through a cloth shopping bag, or filter liner, you will not need to pass the oil thru ore than one rated filter, especially if the shopping bag or liner is collecting most of the fats.

I take some T shirt material (old T shirts are plentiful here) and sew up a bag the same width as the filter bag, but about 2" longer.
I put this liner in the filter bag and fold the excess length back on the outside of the filter bag, to secure it.
As the oil flows thru the filter liner, it will catch any particles which won't pass thru the material.
If you are cold filtering, then any fats will also be captured.
When the liner has a fine layer of fat on it, the fat becomes the filter medium and the oil must 'percolate' thru the fats to pass thru the liner and filter bag.
This technique has the ability to filter much more finely than the filter bag.

The only disadvantage is that it takes much longer than hot filtering, where the oil is hot enough to not allow fats to solidify.
To overcome this slow filtering, I use several bag filters to provide the filtering capacity I need.

Remember that oil filtered in Summer but stored until Winter will have fats in it which will solidify in winter. These fats can cause issues with filter plugging if a heated fuel system is not used.


16th October 2012, 02:39 AM
Thanks Tony that really clears things up. So basically I'd be good with like a 1 or 2 micron sock filter (which you would suggest?), with a filter liner inside of it, draining into a barrel or other storage container.. and then it's ready to be blended? Wow that is a lot easier than I expected.

Tony From West Oz
16th October 2012, 09:53 PM
There is so little difference between 1 and 2 micron filters that unless your vehicle has a common rail injection system it will make no difference to fuel quality, especially if you are cold filtering.

Enjoy the ride,


17th October 2012, 12:06 AM
Ok ok, great.. so really either/or huh? It should be one of those, either 1 or 2 micron, and not any larger right?

Sounds easy enough to me. And yes I will be cold filtering, even if it takes much longer. Nights are below freezing here for most of the year and days can be quite chilly too.

So what if I got one of those 5 gallon bucket sized filters, put it on a bucket, then cut a hole in the bottom for say a 1" pvc, then had that going down into a 55 gallon barrel (hole for the pvc in the barrel lid). With a filter liner in place this should be a good setup right?

And again, thank you very much Tony. I didn't even realize this was an Aussie forum before I joined, thanks from the USA.


Tony From West Oz
17th October 2012, 12:38 AM
That sounds good.
With regards to filter specifications: Providing that you are filtering your fuel finer than the specified fuel filter filtering specifications, then you should not have problems.

Issues may arise where you have an untreated steel fuel tank (usually an after - market tank added for the WVO) which has heating in it, heated fuel returning to it and/or the fuel system has bare electrical terminals in it (eg water sensor in oil filter or sensors in IP). In these cases it is possible that the WVO used in the steel tank will suffer from an increased rate of oxidation. In some cases people have cut the top of the WVO tank open to reveal a thick layer of a rust coloured jelly like substance lining the tank walls. Indications are that this is polymerised WVO.
This does not appear to be a significant issue in factory fitted fuel tanks, in cases where the return is looped back to the IP inlet and/or where there are no electrical connections exposed to the WVO fuel.

18th October 2012, 08:23 AM
I've read about polymerization and was worried about that.. both of the tanks on my F250 are steel, as far as I know. Would polymerization be an issue even if I am running a blend, or would it still be best to have an auxiliary tank?

Also I'm not sure about the looping of the fuel on my 6.9L, would it not be a significant issue since it's factory fitted?


18th October 2012, 12:50 PM

if your climate is so cold then I would blend and I'd even put some kind of fuel agent in my storage tanks.

With regards to cold filtering and upflow settle I think your filtering micron rating is probably a little high. most in car filter mediums are about 7 to 10 microns. I have asked many suppliers so this is only the given knowledge from suppliers.

2 microns is going to cause the flow rate to be really slow. My suggestion would be 10 microns or even 20 but only if the upflow settles over a period of a couple of weeks. you could filter at 50 microns and then use a centrifuge if you can get one cheep.

As for the looped fuel return , are you talking looped back into the incoming fuel line after the fuel filter so the fuel stays warm ?? in your climate this would be a nice option to keep the fuel warm all the time and would avoid the tank fuel oxidization problems.

good luck


18th October 2012, 09:34 PM
Hi All,
Like Tony recommends, keeping everything as simple as possible is a good way to go.....ie cold gravity filtering through a bag filter with a disposable liner in place.

I use the recommended T shirt material inside a 1mic sock filter. I have two side by side actually to double the filtering rate. In Sydney ambient temps the flow rate is fine. As I wander by my setup I hand pump directly into the two filters from the drum which has the course filtered oil in it. Each holds about 8lt (couple of US gallons) so by later that day or next morning the filters are empty and i refill.

The BEST thing that you can do Zac to get good oil is let any oil that you collect settle undisturbed for as long as possible in as large a contain er as possible. then only draw from the very top for filtering. over time it is quite surprising how much crystal clear oil can be drawn from what you collect. Becasue I settle for a long time i rarely need to change the T shirt material.

This is a little dependent on the type and quality of used oil that you collect but extended settling can do amazing things with most oils. Where in the US are you located, what ambient temps do you experience and what type of WVO will you be using?

The experiences with polymerisation have been quite mixed. Some people have had very bad experiences with clogged tanks and fuel systems while others havent. We know that the contributors are heat, air and exposed ferrous surfaces. Having said that though i ran a 1988 Nissan Navara for several years and had no problems. I tried to keep the tank as full as possible and maybe this reduced the exposure to air.

19th October 2012, 08:07 AM
There's lots of info on this site and the great thing is that people will help. Methods and opinions can vary widely.
Each person has their own systems and ways of approaching the issues that blending presents.... and there's absolutely nothing wrong with that.
You'll save a huge amount of money over time but you'll need to be handy with ironing the bugs out from time to time.
So I suggest spend some time studying the forum posts, perhaps a few hours a week... then make a start.
Good luck.

19th October 2012, 09:20 PM
Re the polymerisation,
I meant to add that I still have the Navara but as a farm vehicle for the last 3 yrs. It is used several times a day and it still runs fine on diesel/WVO blends. The only modification to it is and MB prefilter. I have to admit that the tank is generally well below half most of the time so I guess that knocks my 'keep the tank near full' theory on the head.

The old girl continues to start and run fine. One thought that I just had however is the way i start it. Knowing how difficult it will be when the time comes to replace the GPs and as the GPs have a long warm up time prior starting, instead of using them I most often give a very small squirt of ether based tractor start.

The Navara starts instantly and on almost all occasions there is no big end knock to be heard. Just maybe this prevents or more accurately doesnt allow for any injector gumming as there is no extended cranking time when cold blend is being pumped through the injectors.