hi guys,

quick query for you. as you may or may not know, i have a mk3 golf turbo diesel (with added intercooler) and i have located a place only 3 miles from me which sells 100% biodiesel for only 70p a litre, compared to £1.08 a litre of normal diesel at the pumps by me.
is this good to use on my motor or should i use a mix of say 50% bio and 50% normal diesel.

any advice very much appreciated.

Sal

using the mix might be your best bet as you can try to avoid getting a leaky pump.

if you want to try to re-seal your pump you can buy one of those kits, or have peace of mind and let a professional do it for you.

the fuel savings alone from a rebuilt pump running the biodiesel should pay for the pump rebuild after a few years.  the added benefits are cleaner emissions, and more lubricity.

using the mix might be your best bet as you can try to avoid getting a leaky pump.

if you want to try to re-seal your pump you can buy one of those kits, or have peace of mind and let a professional do it for you.

the fuel savings alone from a rebuilt pump running the biodiesel should pay for the pump rebuild after a few years.  the added benefits are cleaner emissions, and more lubricity.

If the biodiesel makes your pump leak, ULSD would have done exactly the same. Biodiesel (or ULSD) will not make a brand new pump leak, only one that has been exposed to Low-Sulphur Diesel for some time (tens / hundreds of thousands of km's). So basically, B100 (or biodiesel in any quantity) is not going to damage your pump unless it's either low-quality fuel or the pump is already hurting, but not presenting any obvious SYMPTOMS yet.

I am Giles' apprentice here at Performance Diesel Injection, just so that you know. We often have different opinions on biodiesel / renewable fuel matters, but I'm not contradicting him either.  

There are a whole bunch of reasons why Bosch doesn't recommend anything above B10 - Giles and I were just having this discussion, because when we see a "Biodiesel" pump, it's because it's gummed up, pitted, rusted and destroyed - usually by bad biodiesel or biodiesel that wasn't properly created or prepared, but not by the simple fact of running on biodiesel. He isn't really a fan of biodiesel, and really disliked it until just lately, now he's a little more neutral. I on the other hand, am a big fan.

The simplest answer as to why Bosch doesn't "recommend" greater than 10% is that nobody has done long-term, life-cycle laboratory tests on the effects of biodiesel on their pumps. Since they can't guarantee that it's going to function properly, they don't try to.

The longer answer is this: in 2005 (most recent stats I could easily find), we used 56,000,000,000 gallons of diesel fuel. The National Biodiesel Board is hopeful that we might be able to produce a grand total of as much as 300,000,000 gallons of biodiesel for this year. The upshot of that is that now, after half a decade of development of the biodiesel industry, it could account for as much as 0.5% of the diesel fuel consumption of the United States, IF it is all burned domestically and none is exported. That doesn't exactly sound like a sufficient market share to bother with the level of testing that would be necessary, right? And that is the biggest reason right there. There are also a variety of feedstocks (oils like canola, soy, waste vegetable oil etc.) available, of varying qualities. There are many smaller manufacturers, as opposed to a handful of more-or-less consolidated major players in the petrodiesel production business. That presents greater variability in fuel quality, as well as a larger possible number of potential points of error or negligence.

Biodiesel remains the product of an industry which is in its infancy, and it operates on a completely different scale than the petroleum industry, so it's not really worth the time and energy investment to test it, particular given the confounding factors of different feedstocks, changing test specs for the fuel, etc.

Aside from that, though, Bosch doesn't warranty ANY work caused by fuel problems, no matter what that problem is. The care and feeding of your engine is your responsibility, and if they can demonstrate that the fuel you gave it didn't conform to the ASTM spec for diesel fuel, then they can legitimately refuse warranty coverage. If you were to try and set up your own fractional distillation tower, get some crude oil and refine it into its components, then use that diesel fuel, you would still not be covered.

But biodiesel itself isn't a problem, the problem is the fact that there are such variations in quality and the fact that Bosch (or other manufacturers) can't say "Yeah, use it, it'll work fine!" because then somebody will make a  bad batch and blame the manufacturer when their engine fails.

Does that all make sense? There is a difference between what the manufacturer acknowledges will work and what the manufacturer is comfortable guaranteeing. But the bottom line is that properly made biodiesel which conforms to the ASTM spec for biodiesel (ASTM D6751-07b) will not harm your pump. Properly made biodiesel, meeting these specs has better lubricity and higher cetane than petrodiesel. It offers equivalent or reduced emissions in all areas except for NOx, which is still unclear - in stationary applications and tests, NOx from biodiesel is increased. In driving conditions, it may be equivalent or lower, but those tests have yet to be done. At the same time, Biodiesel made by someone who is negligent or fails to understand the processes involved, or otherwise doesn't / cannot adhere to production practices which yield such a substance, will damage your pump in short order, just the same as bad diesel fuel that doesn't meet the required spec (ASTM D975-07b) will damage your pump and/or engine in very short order.

So is biodiesel destructive? No. Is all biodiesel the same? No. Should everybody make use of it? Not necessarily, because quality is still loosely enforced and hard to verify. But will it destroy your pump? No, and that's not what the manufacturers are saying - all they're saying is that (I'm paraphrasing, not quoting) "Biodiesel blended in no more than 10% will not adversely affect any characteristic of normal diesel #1 / #2, nor will it adversely affect your pump's operation in that proportion, and they are so certain of that that they won't reject your warranty out of hand for using a B10 blend."

Hope this answers your question without making it sound like Giles and I are saying two different things. We both stick to the manufacturer recommendation in terms of what we can support, but this hopefully sheds more light on why the manufacturers take this kind of a position relative to biodiesel.

That part is definitely true. Biodiesel's energy density is about 10% lower than that of diesel #2 (very comparable to diesel #1) so your mileage does usually drop a bit going from summer diesel to B100. Depending on the fuel and the engine, the improved lubricity of biodiesel tends to partially make up for that - I experienced a 3-5% mileage drop with B100 for that reason.

My fuel pump was rebuilt a couple of years ago, before I started using B100. No leak problems since then.

I have been using B100 for over 2 years now and quite like it. It runs cleaner and quieter but will decrease your mileage somewhat , maybe 10% or so. I use Canola base stock so my fuel is good to about -6 without blending. If it gets cold I blend 40-50%. Have only had to do this once last year. I put a jar of fuel in my carport and if I see crystals/cloudiness forming then I mix in some reg diesel. I have had to replace my injector return lines with viton but so far no problems with the IP seals. Cheers Dan

where do you get viton return lines?  i'm running regular diesel and mine always seem to be leaking.  (they're even new FFS!!)

so hopefully viton will cure that problem for me.  thanks

BeJamminR- Thanks for the great post.  My question for you is, do you expect the pump seal life to be the same using B100 summer alternating with B0 winter, as with dino year round all of the time?  I get top quality biodiesel here (the maker warrantees the product).  I will have you folks rebuild my pump at some point, and I have heard so many different stories it is hard to know what to think.  Bio is the future, and I'd like to move toward it intelligently.
P.S.-  how do different lines react- polypropelene, N-butadene, silicone, urethane, etc?

if the seals in the pump were never exposed to the older non ULSD diesel, then they should be ok.  plus the new seals should be 100% biodiesel safe.

I'm glad to hear that you plan to have Giles rebuild your pump for you, and I think that you'll be glad you did it whenever you get around to it. I'll only be tearing it down and cleaning it up - when it comes to the rebuilding, that's still entirely his department for now at least. :wink:

BeJamminR- Thanks for the great post.  My question for you is, do you expect the pump seal life to be the same using B100 summer alternating with B0 winter, as with dino year round all of the time?  I get top quality biodiesel here (the maker warrantees the product).  I will have you folks rebuild my pump at some point, and I have heard so many different stories it is hard to know what to think.  Bio is the future, and I'd like to move toward it intelligently.
P.S.-  how do different lines react- polypropelene, N-butadene, silicone, urethane, etc?

That one depends significantly on the quality of the biodiesel that you're getting. Biodiesel *is* a solvent, but properly-made biodiesel is a relatively weak solvent. As jtanguay pointed out, if the seals were not exposed for long periods to Low Sulphur Diesel or other substances to swell them up, then biodiesel of ULSD won't have the mentioned effects - the swelling isn't due to any property of biodiesel in isolation, it's due to that property combined with the properties of the Low Sulphur diesel and long exposures previous to long-term B100 usage.

As far as the different lines - my understanding is that only "natural" rubber lines suffer any degradation whatsoever as a pure result of biodiesel's solvent properties, and even that is reduced if the manufacturer takes care to minimize the presence of excess catalyst (sodium methoxide), free lye, and/or free methanol, or if they do an acid / base quench to more-or-less stabilize the pH. To clarify, I mean EITHER an acid OR a basic quench to neutralize the fuel's pH level, depending on which method(s) (acidic or basic, or combination) were used to make it in the first place.

But I can really only offer you conjecture on the reactions of biodiesel with the specific lines that you mention; it is my largely unscientific opinion, supported by anecdotal evidence, that the polypropelene, silicone, and urethane lines should be more or less impervious. I believe N-butadiene in this context is referring to nitrile rubber, correct? If that is the case, then I don't imagine that biodiesel will have a problem with it - there's a lot of confusion over the "natural" rubber vs. "nitrile" rubber issue in biodiesel circles, so many people mistakenly say that nitrile rubber will be eaten by biodiesel.

As I may have already mentioned in this thread, I've logged in excess of 10,000km on biodiesel, and none of my lines (all stock) have been degraded in any way. When I cleaned my injectors the other day, I didn't even need to replace any of my returns - their integrity was still such that I could just put them back on as they were. Again, unscientific and anecdotal, but I'm comfortable making recommendations on such a basis, as long as they don't run contrary to manufacturers' positions.