View Full Version : Cloudy oil

27th April 2013, 09:24 PM
I'm new to making biodiesel and am having some problems. I've titrated my use fry oil at 8ml and 9ml. I've been told to aim to find oil that titrats under 6, so I have very dirty oil. For some reason the first 30L looked good so I put it in my ute. The second round has stayed cloudy and might actually be getting worse the more I wash it (about 6 times so far).I'm confidant I got the methinol castic soda mix right because when I titrated it again the mix went magenta instantly. What is the cloudiness from?

27th April 2013, 11:00 PM
Hi Bilby,
Welcome to the forum.
The cloudiness will almost certainly be from water.

28th April 2013, 08:23 AM
Thanks Tilly

I heated the cloudy biodiesel on the stove yesturday and kept it at 60-70C for at least half hour. This morning it hasn't cleared. Can you tell me what to do to clear it?

28th April 2013, 09:30 AM
Hi Bilby,
If I am trying to dry 30 litres of biodiesel I bubble air through it using an aquarium air pump. I tie a weight to the end of the plastic hose and drop the weighted end of the hose to the bottom of the pail.
Be sure to have the pump above the top of the biodiesel and remove the hose from the biodiesel when you turn the pump off. Most aquarium pumps are not biodiesel compatible.

28th April 2013, 03:20 PM
Thanks Tilly

Can you now tell me how I'll know if the biodiesel is good to put into my ute? I'm assuming colour or lack thereof isn't everything.

28th April 2013, 06:12 PM
Take a small jar (make sure the jar is clear and clean) , fill it 3/4 full with you BIO and place it in the microwave and gradually heat it up - you should see water bubbles rising to the surface and leaving - after a while of doing this ( i do 30 sec at a time and then let it settle for 1 minute before i do the next one) you should see the bubble stop rising - this will mean your BIO is dry for all intents and purposes - note the colour and clarity now. This will give you some idea of what you are aiming for.

Once it cools down you may find it darkens down in colour again - try heating again just to make sure you have got rid of all the water.

Once this has cooled down - take 1/2 the sample and put it in another jar - add an equal amount of water and shake vigorously - then let sit - within a couple of minutes you should see the BIO and water seperate and the water should be crystal clear - if it isnt then you probably have not washed your BIO well enough

Take the other 1/2 of the sample and do a 3/27 or a 10/90 or whatever other meaurement you use to ensure you have high rate conversion BIO


28th April 2013, 07:35 PM
Hi Bilby,
You are correct, colour is not a reliable indication of quality.
What type of car and engine do you have?

I have a Musso with an "Old Technology" Mercedes 5 cylinder engine.
The only test I perform is the "Bright and Clear" test.
If the biodiesel l is bright and clear first thing in the cool/cold of the morning I use it.
If it is cloudy that means it has moisture in it. In that case I will air bubble it until it is bright and clear first thing in the morning.

A lot of people seem to do the Warnqvest Conversion Test located here

30th April 2013, 03:00 PM
Hi Tilly

My ute is a 2010 Nissan Navara, Spanish built. Does that matter? I'm just about to wash my third batch now and it looks really good after the glycerin is removed. What does high conversion biodiesel mean, is it good or bad. So much to learn.

Cheers Rob

30th April 2013, 06:20 PM
Hi Bilbo,

If your car is an automatic transmission it probably has a DPF fitted. That is not particularly good.
If your car is a manual it probably does not have a DPF installed. That is better.

High conversion biodiesel contains mostly Methelesters. Most of the Vegetable oil has been converted to biodiesel/methylesters.
I think of around 97% or better conversion as high conversion.

High conversion biodiesel is never worse than lower conversion biodiesel. However, some diesel engines, such as mine, do not require high conversion biodiesel. It will run fine on lower conversion biodiesel just as well as high conversion biodiesel. My engine is an "old Technology" 5 cylinder Mercedes diesel with inline injector pump and indirect injection.

On the other hand your diesel is a new technology direct injection high pressure common rail system. As far as I know, it is an unknown. A lot of people have reported success using biodiesel in common rail direct injection engines.

Many people will tell you you must use high conversion biodiesel in your engine. I suspect most of them would only be guessing.
I have not seen the definitive testing on this.

I can not advise you as to what type of biodiesel to use or even if you should use biodiesel.

Please keep us informed as you progress.

2nd May 2013, 05:08 AM
Tilly; Could the cloudiness be from calcium soap? Where the source of the calcium is the wash water.

2nd May 2013, 10:26 AM
Hi Wesley,
I do not know how to make that determination.
"Common Knowledge" is that if you water wash biodiesel the cloudiness is moisture in suspension in the biodiesel and it needs further drying.

I have found that when drying newly washed biodiesel in a pan on the stove, it will become clear as it approaches 100 deg C. As I take the temperature above 100 deg C, water will usually settle out onto the bottom of the pan. Of course care has to be used to avoid injury from spitting oil as the temp approaches 100 deg C
Then, when I allow the pan of biodiesel to cool, the biodiesel again usually becomes cloudy.
If I now decant this biodiesel into another pot, being careful not to include any of the settled out water and reheat this biodiesel it will again become clear.
At this point I limit the temperature rise to around 105- 110deg C and continually stir the biodiesel with my thermometer until all signs of moisture coming out of the biodiesel ceases.
At this point, when I allow the biodiesel to cool it stays clear and bright until it reaches it's gel point.
In that situation I am pretty confident that the cloudiness is moisture.

Hiw much calcium soap is produced while water washing?
Will calcium soap make biodiesel cloudy?
Is this cloudiness temperature dependent?
Will the soap be permanently removed from the biodiesel if left to sit in an open top container?
Will the soap be permanently removed if you bubble air through it?

3rd May 2013, 01:38 AM
I assume this water washing is not done with distilled water. So, From Wikipedia; Calcium Stearate is a carboxylate of calcium. It is a white waxy powder. It is the main component in soap scum, a white solid that forms when soap is mixed with hard water. Unlike soaps containing sodium and potassium, calcium stearate is insoluble in water and does not lather well. Slightly soluble in oil. Insoluble in water, alcohol, ether. Density 1.08 grams per millilitre, melting point 155 degrees centigrade, white to yellowish powder. Maybe in this water washing, the soap is forming some calcium soap that will not wash out with the water. The density difference between biodiesel and calcium soaps isn't a lot. I'm just saying there might be some of this in the cloudy, water washed biodiesel. Other dissolved minerals are in water, so a little of other types of water insoluble soaps can probably form. Not just calcium soaps.

3rd May 2013, 03:38 AM
Hi Wesley,
Maybe in this water washing, the soap is forming some calcium soap that will not wash out with the water. The density difference between biodiesel and calcium soaps isn't a lot. I'm just saying there might be some of this in the cloudy, water washed biodiesel. Other dissolved minerals are in water, so a little of other types of water insoluble soaps can probably form. Not just calcium soaps.I guess anything is possible.
I spent about 9 years water washing with hard water and was always able to dry my biodiesel to "Clear and bright" without any particular problems,
especially once I started bubbling air through it.
I can not recall ever reading that calcium soap production was a cause for biodiesel not clearing.