Don't mix biodiesel with diesel in your tank.

Diesel Addict

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I can see from the postings here that a lot of people are still not aware of this. Take it as good advice. Biodiesel has higher water solubility than diesel and when the two are mixed some water may drop out of the solution. This water is normally drained from the bottom of storage tanks by professional bio producers. If you mix the two in your fuel tank, there's a good chance you'll get some water in your fuel system. If you want to use bio as a lubricity additive or whatever, buy it pre-blended straight from the pump. Don't blend it in your tank!
 

BKmetz

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This is called 'splash mixing' and is highly discouraged. The two fuels have just enough difference is specific gravity and polarity that water can drop out and the two fuels can form separate layers in the tank. Not good if one is trying to run biodiesel in winter.

All VW TDI fuel filters used up until the PDs have a water drain on the bottom of the filter. The TDI models did away with the little water separator tank with the electric water sensor back under the vehicle by the fuel tank.

John, you need to take a closer look under the hood! The fuel filter is in plain sight on the passenger side between the air box and the strut tower. If its not there, someone really messed around with your car.





:)
 
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aja8888

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BKmetz said:
This is called 'splash mixing' and is highly discouraged.
:confused::confused: BK: I don't understand your comment. I use one quart of soy-based biodiesel (bought from Houston Biodiesel) per tank of D2. I put the quart in after the D2 fill when I get home. I buy the biodiesel in 5 gallon increments and store it in a poly container.

Am I doing something wrong or not recommended?

Thanks,

Tony
 

BKmetz

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I edited my post to add more info on what happens.

Splash mixing does not guarantee the fuels will properly mix. There is some mixing, but it depends on the source of the bio, how the bio was made, water content, etc. There 'could' be stratification in the fuel tank, especially if the car sits a while after adding fuel. This is really a problem for people using bio in winter. A quart isn't going to matter but 5 gallons sure could. If you could see the inside of the tank you would see that most of the mixing occurs when you are driving around.

The water separation is mostly an effect of poorly made bio.
 

UFO

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On warm days like this I don't hesistate to pump a few gallons of B100 into the tank. If it's cold I just pump B50 or whatever I have already mixed. I would hope most would not be adding much bio into the tank when it's cold; that's when I'm splash blending in some D2 to give me insurance from gelling.
 

naturist

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aja8888 said:
:confused::confused: BK: I don't understand your comment. I use one quart of soy-based biodiesel (bought from Houston Biodiesel) per tank of D2. I put the quart in after the D2 fill when I get home. I buy the biodiesel in 5 gallon increments and store it in a poly container.

Am I doing something wrong or not recommended?

Thanks,

Tony

yes, Tony, you are.

Because the biodiesel has a lower density, it will have a tendency to just lay there on the top of the diesel layer and not mix properly. It would be much better if you put the biodiesel into a 5 gallon jug, filled it with diesel, mixed it up good by shaking, and put it into the tank before topping off with diesel. At the very least, put the biodiesel in first before pumping anything into the tank.

Beyond that, I see you are in Connecticut . . . biodiesel and diesel also mix very poorly when either is below 40 degrees F. You would be much better served by mixing that 5 gallon jug after storing both parts in the house for a day or two, where they will be warm, and mixing one last time, before you put it in the tank, and top off.
 
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aja8888

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naturist said:
yes, Tony, you are.

Because the biodiesel has a lower density, it will have a tendency to just lay there on the top of the diesel layer and not mix properly. It would be much better if you put the biodiesel into a 5 gallon jug, filled it with diesel, mixed it up good by shaking, and put it into the tank before topping off with diesel. At the very least, put the biodiesel in first before pumping anything into the tank.
I was thinking about doing that as I have a 2 gallon fuel can available. Makes sense. I really just started this addition process to get the best lubricity I can since we have a great supply of quality biodiesel here.

Thanks,

Tony
 

Diesel Addict

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I didn't even think of the two not mixing well together, but then again I would never just top off my tank with something other than what's already in the tank and expect it to mix well. Even with regular fuel additives it's recommended to put them in BEFORE filling up. Mainly I'm just trying to warn people of the potential for water dropping out which was noted and mentioned to me by a local biodiesel start-up company a few years ago. The manager warned me against splash blending in my tank and said they get noticeable water accumulation at the bottom of their storage tanks which they have to drain out.
 

TomB

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Diesel Addict said:
I can see from the postings here that a lot of people are still not aware of this. Take it as good advice. Biodiesel has higher water solubility than diesel and when the two are mixed some water may drop out of the solution. This water is normally drained from the bottom of storage tanks by professional bio producers. If you mix the two in your fuel tank, there's a good chance you'll get some water in your fuel system. If you want to use bio as a lubricity additive or whatever, buy it pre-blended straight from the pump. Don't blend it in your tank!
I have 7 years, 170K miles and four vehicles of experience with BD to contradict this statement.

Using a pump/nozzle will mix this in your tank, so not sure where you are getting this from.

Again, quality BD does not have this issue and they should be using a water filter cartridge on the BD pump to catch any moisture that may be there.
 

AUS_TDI

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?

What, don't you guys drive your cars after filling up?
No way you are going to get stratification, non-homogenous mix maybe.
 

naturist

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AUS_TDI said:
What, don't you guys drive your cars after filling up?
No way you are going to get stratification, non-homogenous mix maybe.
Of course we drive 'em. But the amount of "sloshing" around is low, unless you manage to get upside down several times. A good roll down an embankment will do the job, but just driving down the road won't. If you'd like proof of this for yourself, fill a half-liter soda bottle (glass preferred, clear, colorless, so you can SEE what happens) about 2/3 full of diesel, then add a layer of biodiesel on top. Leave some air space in it, and put it in your cup holder as you drive around. You'll find it'll just sit there on top, no matter how many weeks you drive around with it in that cup holder.
 

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Biodiesel / D2 blending discussion starts at slide 13 of the link below. See pics on the stratification. Note that with splash loading to make B20, there is virtually no immediate stratification but some after 24 hours. I doubt that splash loading a quart of B100 to a tank of D2 (to make about B2 for lubricity purposes) will be of any consequence especially if the car is driven daily. But draw your own conclusions. I certainly wouldn't splash blend much higher.

http://www.cdc.gov/niosh/mining/topics/diesel/elkoworkshop0607/4b-Campbell.pdf
 

AUS_TDI

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The statement was pump in one liquid into another liquid.
Instead of looking at a small container inside a vehicle look at what happens inside a long 40-50 litre tank with baffle plates.
Also you have fuel being recirculated back into the tank all the time from the pump.
Again no way that fuel is going to stratify.

End of rant
 

Lug_Nut

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Diesel Addict said:
Mainly I'm just trying to warn people of the potential for water dropping out which was noted and mentioned to me by a local biodiesel start-up company a few years ago. The manager warned me against splash blending in my tank and said they get noticeable water accumulation at the bottom of their storage tanks which they have to drain out.
I'd be more wary of that supply of wet biodiesel. When biodiesel is saturated enough that water precipitates out it is far beyond suitability as a fuel or as a lubricity aid.
I've been splash blending about 4 months a year for the past 8 years, just starting my 9th year. The drive home from the petrodiesel station is sufficient to mix the two. The poor analogy of a pop bottle in the cup holder does not even closely mimic the fuel tank shape. Set the pop bottle sideways, more horizontal than vertical (like the fuel tank), and you'll see how quickly the two mix.
 

mannytranny

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I have been splash blending B50 in 4 vehicles this way for 4 years. I do live in Southern Ca, so that may have something to do with my lack of problems...

I do try to add 5g of B99 and 5g of diesel on top of it, but that is not always. I think that once the vehicle gets rolling the convection in the tank and the sloshing around of the fuel works to mix the solution pretty well.

I've never found a drop of water in any of my fuel filters, and when I recently opened my injection pump (to fix that pesky head seal) I found the pump to be quite clean and in good working order.
 

barshnik

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A few weeks ago I poured 1/3 of a shot glass of bio from the 2 gallon can that I get filled from a friend of mine that home brews bio into a 16 oz. clear plastic soda bottle (cleaned & dried), filled with diesel at a recent fill up, and gave it ONE quick shake. That translates to the 2% that I've run since new, always pouring 1 quart into the tank before a full fuel fill (proprtionally less for less than a full tank fill). That bottle is as totally mixed without any seperation as the day I filled it, and I'd notice as the bio is a bit darker than the pure diesel. I'll trust my own eyes, and for the tiny bit (2%) of bio that I run, I think splash-mixing is fine.
 

BKmetz

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The take home message is that splash mixing CAN be fine, or it can cause problems. Lots of variable to consider, cliamte being one of them. If one lived in a derert climate like NV, then they probably would never see any problems. That doesn't translate into good advice for people living in other areas.

barshnik said:
A few weeks ago I poured 1/3 of a shot glass of bio from the 2 gallon can that I get filled from a friend of mine that home brews bio into a 16 oz. clear plastic soda bottle (cleaned & dried), filled with diesel at a recent fill up, and gave it ONE quick shake. That translates to the 2% that I've run since new, always pouring 1 quart into the tank before a full fuel fill (proprtionally less for less than a full tank fill). That bottle is as totally mixed without any seperation as the day I filled it, and I'd notice as the bio is a bit darker than the pure diesel. I'll trust my own eyes, and for the tiny bit (2%) of bio that I run, I think splash-mixing is fine.
 

Lug_Nut

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Some colder climate advice, take it if you wish, or ignore it.

Know your bio's gel point. Don't even attempt to splash blend bio in into petrodiesel that is colder than the bio gel point. The B100 will gel up like you were dripping chocolate onto ice cream. Now THERE'S stratification!

If you absolutely insist, you can gain a few degrees by splash blending colder petro into bio that is still above its gel temp. The petro won't gel as it hits the slightly warmer bio. The percentage of petro in the tank starts at zero. As petro volume is added the reduction in the average tank content temperature will drop (colder petro), but the gel temperature will also go down.
This won't gain much, but there enough difference when temperature conditions are borderline to avoid gelling before completing the 2 mile drive needed to thoroughly mix the two.
 

naturist

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barshnik said:
A few weeks ago I poured 1/3 of a shot glass of bio from the 2 gallon can that I get filled from a friend of mine that home brews bio into a 16 oz. clear plastic soda bottle (cleaned & dried), filled with diesel at a recent fill up, and gave it ONE quick shake. That translates to the 2% that I've run since new, always pouring 1 quart into the tank before a full fuel fill (proprtionally less for less than a full tank fill). That bottle is as totally mixed without any seperation as the day I filled it, and I'd notice as the bio is a bit darker than the pure diesel. I'll trust my own eyes, and for the tiny bit (2%) of bio that I run, I think splash-mixing is fine.
It's the "one quick shake" that does it, barshnik. The thing is that your fuel tank doesn't get "one quick shake" unless you roll the car upside down at least once. You might get a good mix putting the bio into a nearly empty tank, and then filling with petro d2. Indeed, if you are only blending to B2 in the first place, you are right, you are probably fine. And at that low concentration, complete solubility is probably assured.

It is when you blend to higher proportions of biodiesel that "splash blending" is more likely to get you into trouble with stratification.

I am a chemist, and I've made blends of commercial soy biodiesel from 10% to 90% LOOKING for stratification (as well as for gel protection). And I can tell you for a fact that I see it, especially in blends around 50/50. In fact, at 50/50, it is difficult to avoid it without several minutes of vigorous agitation.

Our aussie friend who insists the normal jiggling of a car in travel combined with the trickle of fuel being recycled to the tank will prevent stratification is simply wrong. I've done the tests. He would know better if he had done them, too.

If you want to see really pronounced stratification, put two small bottles of petro and bio into your refrigerator. Equal volumes of each. Let 'em chill below 40 degrees F, and pour them together. Shake the h**ll out of the mix and put it back into the 'fridge so it doesn't warm up. Note the cloudy appearance of the mix. This is one sign that it is NOT a homogeneous mixture.

You will find the next day that there is no doubt there is stratification. It is well known in the fuel industry that while EVENTUALLY biodiesel and petrodiesel will completely dissolve in each other, REAL mixing is needed to avoid stratification. While they do dissolve in each other IT ISN'T INSTANT.
 

Diesel Addict

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BKmetz said:
The take home message is that splash mixing CAN be fine, or it can cause problems. Lots of variable to consider, cliamte being one of them. If one lived in a derert climate like NV, then they probably would never see any problems. That doesn't translate into good advice for people living in other areas.
Why would the desert climate of NV not present problems? Something to do with humidity?
 

Diesel Addict

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TomB said:
I have 7 years, 170K miles and four vehicles of experience with BD to contradict this statement.

Using a pump/nozzle will mix this in your tank, so not sure where you are getting this from.

Again, quality BD does not have this issue and they should be using a water filter cartridge on the BD pump to catch any moisture that may be there.
Sounds like you're missing the point. The point is that water may drop out of the solution in your fuel tank after you mix the bio and diesel. It has nothing to do with whether the BD pump that you use has a water filter cartridge.
 

Diesel Addict

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Lug_Nut said:
I'd be more wary of that supply of wet biodiesel. When biodiesel is saturated enough that water precipitates out it is far beyond suitability as a fuel or as a lubricity aid.
I've been splash blending about 4 months a year for the past 8 years, just starting my 9th year. The drive home from the petrodiesel station is sufficient to mix the two. The poor analogy of a pop bottle in the cup holder does not even closely mimic the fuel tank shape. Set the pop bottle sideways, more horizontal than vertical (like the fuel tank), and you'll see how quickly the two mix.
That "wet" biodiesel was fully in compliance with ASTM specs. Water in fuel is harmless as long as it's dissolved in the fuel. It's when you get a separate water layer that you are likely to run into trouble.
 

Lug_Nut

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The ASTM limit of water in biodiesel is 500 mg/kg (.5g/1000g, or 1:2000)
The solubility limit is about 1500 ppm (1500/1000000, or 3:2000)
Water separated out of the fuel indicates that the water content dissolved in the saturated fuel is THREE TIMES over the water limit of ASTM biodiesel.
 

kcfoxie

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I suppose I can see this if you're aiming for +10% and live in Minnesota, but below 10% and above 40F I don't see the problem.

drive more worry less.
 

CsTDI

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so, in theory that fuel will not mix but will eventually dissolve into each other :confused:

I have been splash blending BD in the northeast in the summer and winter with PS and have not encountered the obvious problems of what I think that you are saying- namely that the BD would float on the top of the fuel in the fuel tank and I would eventually be running 100% BD??

Since premixed BD in not also being cited as a problem. How do you think they are premixing it? Shaking up vats? adding an additive that causes the BD to blend with D2?
 

kcfoxie

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E10 is splash blended in the tankers by the Selma outfit here in NC.

B20 I want to say if purchased from the Wilson guys at Triangle Biofuels is actually run through a "blending" tank.

However I think most places splash blend the two in the trucks. Some trucks have recirc systems in them that mix the fuel as it is being traveled.
 
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