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Old 11-23-2007, 05:58 PM   #1
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I have read in a recent post and elsewhere that pure biodiesel (b100) will degrade certain seals and can leave deposits. I suppose you could replace the seals, hoses and gaskets that are susceptable with a resistant substitute but how can you deal with deposits and clogs in the fuel injectors. Is it cost effective to run pure diesel in a vehicle or have you guys found it better to run a blend. Anyone out there who runs pure biodiesel please let me know what mods you performed on your vehicle and the difficulty/cost. Sorry to ask so many questions but I am finding mixed views elsewhere. Some say go ahead and run it pure and others say you are sure to have problems. Just trying to clear up the facts. Thanks


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Old 11-24-2007, 04:07 AM   #2
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Biodiesel is still too new to really have many facts behind it. Quality varies wildly, there aren't any real specifications that are adopted yet (though this is rapidly changing), and it can come from many different sources.

It will eat through regular seals. That is a fact that you need to be aware of. Anything that your diesel runs through will need to be replaced with new tubing. As for deposits, from what I know, it does the opposite of creating them. It actually REMOVES deposits. So, you better have extra fuel filters on hand for when you make the big switch.

Lots of people do earlier oil changes after switching to biodiesel, and I think this is a smart precaution.

Regardless of what kind of car you drive, you should head over to They, as the name implies, focus on the TDI engine that VW uses, but the information can be applied to most diesel engines.

If I were you, I would slowly introduce biodiesel to my car and have my oil tested to check if there are any problems showing up.

Last thing, is depending on how old your vehicle is, you may have warranty troubles. Because of the confusion from having no real standards yet on biodiesel, a lot of companies will void warranties on cars that use a mix greater than B10.

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Old 11-24-2007, 05:41 PM   #3
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I run B100 biodiesel when the temperature here in New England allows, about 9 months of the year. I've been running biodiesel since November of 2001. I have had two instances of fuel related issues, both on the same tank of fuel from a local home 'brewer' who reluctantly released a batch, at MY insistence, before he felt sufficient glycerin settling time had passed. He was right. Additional separation took place in my fuel tank and blocked the intake strainer. I had to remove the sender unit and pick up the chunks. I have since bought only from commercial suppliers and have had no problems with fuel quality. I've gelled a few times by running too high a bio percent when it was too cold, but that's my fault.
Too "new"? Biodiesel has been around as a byproduct of soap production since the middle ages. It wasn't called biodiesel, but it existed, with no purpose other than as a de-greaser. It has been used in diesel engines from only a slightly earlier date than petroleum diesel fuel (called "rock oil" before Rudolph Diesel developed the engine).
There are several specifications, however they differ. There is a European DIN standard and a separate ANSI standard. These two unfortunately do not overlap and are mutually exclusive of the other. The ANSI standard also has the unfortunate problem of being saddled as an additive that has to meet the ANSI diesel specification. There is no US specification for B100, only for the final blend of the two.
Biodiesel will soften natural rubber and most nitrile rubbers. This is no different than wheel bearing grease or diesel fuel. Inadequately prepared (non-conforming to either DIN or ANSI) fuel may contain residual methanol from the catalytic process used to separate the esters from the glycerin. This methanol will accelerate the softening and leaching of the fuel through the susceptible rubbers. All diesels since about 1996 have been built with methanol resistant (and obviously petro-diesel resistant) fuel system components. The brake hoses and fan belts are not fuel system items and need to be wiped clean of spilled diesel or biodiesel.
Biodiesel, because of its detergency actions (derived from its soap production origins) will dissolve petrodiesel related sludge and gunk. If this accumulation has been forced into gaps and plugged old leaks, then the biodiesel might remove the plug and renew the prior weeping.
I change my fuel filters annually anyway, and the capacity has been enough that even 150k+ miles of petrodiesel dirt wasn't enough to cause issues when I switched cold-turkey to B100. And mine have all been well out of warranty before I can afford to buy them.
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Old 04-20-2008, 10:53 AM   #4
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First, I have used B100 exclusively for years with NO trouble. I know many people personally who have done the same. I love it. I hate to put dino-diesel in the tank. My truck runs so much better on BD it isn't funny. I did not have to make a single modification to run B100 (it's a 1995 truck).

Biodiesel does not cause deposits. In fact it is one of the best solvents known. It WILL eat the paint off your car if you don't wipe it off. The varnish that it cleans from tanks of vehicles that have seen years of dino-diesel may clog a fuel filter, but not everyone sees that. I started using B100 at 100,000 miles and never had to change the filter at all. I have found no evidence that it causes deposits in the engine either (and believe me I looked before I started using it). I replaced a blown head gasket in my diesel after 30,000 miles of B100 use (caused by a broken fan belt, not BD) and the pistons, sleeves, valves, heads, and injectors were clean and bright.

B100 will degrade (not "eat") natural rubber components of a fuel system, but few manufacturers (none that I am aware) have used natural rubber since the late 1980's. Any vehicle made after 1995 will run pure biodiesel with no degredation to the fuel system. Even if there are natural rubber fuel lines in your vehicle, they just get soft and weepy. They do not catastrophically fail and they are easy to spot and replace.

There IS a U.S. biodiesel quality standard. Biodiesel is certified by ASTM. If you get your B100 from a pump it is ASTM certified, just like gas. Of course that is not the case if you make it yourself, or "Joe" down the street makes it; but it is easy to make good quality BD even if you do it yourself. Personally, I just buy mine - it's just too messy to make.

I am aware of no evidence that more frequent oil changes are needed with B100. I have my oil analyzed reqularly, and if anything the change interval is longer with B100. Easily longer than the recommended manufacturer's oil change interval.

Bottom line is I switched cold-turkey to B100 and have never looked back. No failed components, no deposits, no engine problems - just an engine that runs much quieter and smoother, and pollutes much less.
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Old 04-21-2008, 04:39 AM   #5
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I think the seal and hose issues relate to vehicles that were built pre '95 or so, as most manufacturers had went to the more durable replacement, and instarx says this too. I agree.

B100 doesn't carry the same Btu's as diesel. B20 is very close to regular diesel, and even B2 adds a lot of lubrication to ULSD, which is very, very important.

It is a solvent. I can disturb some previous debris.
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Old 04-21-2008, 05:43 AM   #6
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The BTU content varies a bit based on the original feedstock plant oil used in the transesterification process, but typically is about 10% less per unit volume. B100 would be down 10%, B20 about 2%.
One consideration to offset this is the slower burn rate of biodiesel. This allows a longer duration aplication of combustion pressure during the power stroke.
At high, near red-line rpm operation the slow burn rate is a limiting factor as the piston is pulled down by the rod at the same rate as the expansion in the combustion chamber, effectively no application of torque, and no power at an engine speed a few rpm lower than that at which petrodiesel has the same result.
But at lower RPM, the slower engine speed means the longer duration burn rate can exert pressure through a greater degree of crankshaft rotation. This lessens the peak combustion pressure (and the formation of oxides of nitrogen) while at the same time increasing torque.
Dynamometer tests on my VW TDI with B100 biodiesel, and petroleum diesel (A-B-B-A tests) resulted in an increase of power in the 1200 to 2200 rpm range on B100, less power above that, and a maximum engine speed of 4400 rpm versus 4600 with petroleum diesel.
The 1200 to 2200 range encompasses 35 to 65 mph in 5th, so for most of my driving the use of B100 biodiesel is actually able to produce more torque (power) than petrodiesel, or the same power for less fuel use.

re: paint damage, Car paint is nearly impervious to biodiesel. If you've painted it with a latex rubber paint, or an oil based paint, you'll have trouble, and factory finishes may appear stained as the fuel dribbles hold atmospheric dust, but a simple application of car wax will remove the dust and fuel with no damage, even weeks after the spill.

re: fuel lines, The leaching of biodiesel through the walls of petrodiesel resistant fuel hoses, even if they are not specifically biodiesel resistant, is a long, slow process with plenty of time to schedule replacement before the hoses 'leak'.
Non-diesel resistant hoses, such as the windshield washer hose I tried once for a fuel return line, turned into a sodden mass and began leaking as if it were sponge within one day!
I have a 750 cc diesel Mitsubishi powered Bolens lawn tractor built in 1988. The diesel (not biodiesel) resistant fuel hoses are still original. I've been using biodiesel (and blends in the winter) for the past four years. The hoses are messy with grass clippings and dust stuck to the surface film of fuel, but they aren't yet leaking in a loss-of-fuel sense.
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Old 04-21-2008, 05:57 AM   #7
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VW diesel rabbits have the natural rubber hoses, and I did some figuring a few years back, and found that for about $25 you could replace all of the natural rubber hoses with the best chemical resistant hoses available, and the one seal on the injector pump, and you would be good to run bio-diesel, it's so cheap because most of the fuel lines are steel, with about 3 feet of rubber fuel line in total, just in places where it needs to flex.
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Old 05-22-2008, 05:17 PM   #8
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I haven't really had a chance to run B100 in my vehicle, but I was impressed by the B20 I bought once. It's the only thing my Powerstroke like better than offroad diesel. It only makes sense that we switch to BD seeing as how our motors were designd to run on peanut oil, of all things.

In all honesty, I have seen some FE and performance gains running about a pint or 2 cycle oil in a 22 gallon tank. Seems to clean the injectors and give it a slower burn and more compression. Who knows.
2001 Ford F-250 Superduty, 6 speed manual, twin-turbocharged 7.3L Powerstroke diesel dynoed at 627 hp and 923 lb/ft. If you want to know more, PM me.

22 MPG city, 15 MPG highway.
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Old 06-11-2008, 10:06 AM   #9
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I have been running B20 in my 1996 Ford Powerstroke for the past 6 years with no problems. I would run B100, but it is hard to come by. I have run over 100,000 miles on B20 with no seal or oring problems. Occassional I HAVE to run #2 diesel, and I cringe at how much smoke and loss of power I get. Plus my wife likes the smell a heck of a lot better than #2.
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Old 09-13-2008, 06:45 PM   #10
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On occasion I run B50 from Sinclair in my 95 powerstroke. The power seemed better but FE doesn't. I missed a day of work when the thermometer dropped below 50. The tank Jelled and it took 4 hours for the block heater and a heat lamp directed at the fuel lines before the truck would start again.

In the summer I get consistant 19 MPG if I shift below 1800 RPM on #2 diesel. I hope to get an extra 100 horsepower, 230 ft pounds of torque and 22+ MPG with an upgraded chip, exhaust, turbo and intercooler.

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