Friday, April 05, 2013

Bio Diesel, yes or no?


Sunshine Key Rv Resort, Florida (high 82, low 69) thunderstorms

We didn’t take the boat out yesterday because the winds were predicted to be up and we figured it would be choppy.  As it turned out, it was nice and calm and we missed a good boating day.  Al wasn’t feeling great though.  I think he’s trying to get my cold, but so far has managed to fight it off.  I am feeling a lot better, no more coughing, sneezing or any other disgusting symptoms of a cold, but I  am also feeling a bit tired.

So….we decided to run into Key West to pick up some new  tires for the boat trailer.  Al had called and gotten a price for new tires and a new rim so we’ll have a spare.  When we got down there, they told us the price was just for the tire (not what they told him on the phone) and it was way too high. 

We stopped at a NAPA dealer in Key West and picked up two fuel filters for the motor home.  More on that later.  There is another one we need, but of course they didn’t have it at that particular NAPA, so we’ll be running into Marathon for that one.

We stopped at a few other tire places and had zero luck locating trailer tires.  It seemed to be the story of our day.

On the way down to Key West, we ran into the couple that had stayed in the site next to us in Midway.  He was nearing the end of his walk across the country.


He (Arthur) started in British Columbia and over the course of two years has nearly made it to Key West.  They were taking a break on the side of the road, so we quickly stopped and talked to them.  We had only met his driver Valerie before so it was nice to meet the walker himself!   He had less than 25 miles to go, and is killing some time until his grand entrance into the southern most point in Florida on the 14th of April, where he will meet his son.  We hope to bet there to see him complete his journey.   It’s for diabetes, cancer and veterans.


The reason for picking up new fuel filters for the motor home is because of the reading we’ve been doing on the bio diesel fuel.

We’ve  heard that bio diesel fuel can clog up your fuel filters, and until recently were able to avoid it.  When we fueled up before we got into the Keys, we were forced into using bio diesel, for lack of other options.  The station that we always used, now only carries bio diesel.  We checked with the station near Tampa that we fill up with on the way back and discovered the same thing.  In doing a little checking, it appears Flying J has gone strictly to biodiesel and no longer carries ULSD.

So, what do you do?  Run out of fuel or use bio diesel?

Our engine is a Cummins 370 ISL engine.  Al called three different Cummins service centers, and basically got three different answers.

The first guy said to “plan on spending a lot more on maintenance.”  He said there was no additive that would help.

The second Cummins guy said you could use a fuel additive called “fuel prep” that would help.  The problem with that is that if there was a lot of gunk in your fuel tank, it would clog your fuel filters really fast.

The third guy was from the Cummins facility in Spartanburg, SC.  He seemed to be more knowledgeable about the issues with bio diesel fuel.   He said the lower the % of bio diesel the better.  5% is better than 20%.   Once you keep using it, you will clean out your fuel system and the coach will run better, however you may go through some fuel filters in the process.  He suggested we sign up to register to Quick Serve Online, which would keep us up to date with any new information, and any new service bulletins.

While Al was calling the Cummins service centers, I went on line to Rv Net Forum and posted the question for others.  Of course, you have to understand that these are only opinions and you have to weed through them.   The link for my thread is here.  I got some good responses.

Here are a few of the responses I got:


Biodiesel caused issues with the injectors in our 2006 F-250. Had to replace several while it was still under warranty. Part of the problem was cold temperatures in our area, but it was not fun.


Call Cummins direct, as I did and they will tell you 5% bio is all they recommend. Make sure if it is going to set for awhile, that you use a biocide to counter any algae growth from the condensation that will form.......Luckily around here they do not use bio diesel, so no problems.

(the problem with this as I see it, is that the pumps are labeled to be anywhere from 5% to 20% and you won’t know what percentage they use)  You have no choice.

Checked the Department of Energy website. If I am reading them correctly it says that the move to ULSD had the unintended consequence of causing "lubricity" problems and that bio-diesel blends solve this problem with blends as low as 1% bio diesel. But the bio-diesel had the unintended consequence of plugging fuel filters and other forms of damage, especially to older vehicles not designed to tolerate bio-diesel. They also admit that your vehicles warranty might not be any good if you use bio-diesel. What they do not admit is that this mess is all their fault. Idiots.

This next one I thought was interesting

Here is Cummins official position on Biodiesel for your ISL (per bulletin 4971288):
"ISL engines that are certified to EPA '02 and later regulations are approved for use of B20 biodiesel. The appropriate ASTM standards must be met."

I haven’t been able to check the service bulletin out for myself yet, since I need the ESN for our engine before I can complete my registration at Cummins.


The problem with Biodiesel is that it dissolves any gunk that has accumulated in the tank and lines and that is what clogs the filters. The other problem is that the "Bio" part might cause some older fuel lines to dissolve, just like ethanol does. As long as it doesn't sit in the tank, you should be fine. If I have to fill with anything over 5%, I will make sure to run that tank out before putting it away for any period of time. I've had to have several outboard motors rebuilt because of ethanol gasoline, and numerous primr bulbs and fuel lines replaced on small engines. I now have a 110 gallon tank at my house for non-ethanol gas.

(we can confirm this about ethanol)

The reason bio-diesel plugs up the filters is because it cleans your whole fuel system, which a good thing if you carry spare fuel filters and can change them yourself. As stated, bio-diesel has superior lubricity benefits over ULSD and you may notice your engine running smoother and quieter. I've read that bio-diesel will gel quicker than ULSD though, so maybe not a great option in the winter months. I personally like bio-diesel and will use it in the summer months when convenient, but I carry spare filters.


So…..those were a few of the comments I got.  There were others if you care to read them, just go to the link I posted earlier.


It appears the consensus is:

1.  carry extra fuel filters

2.  don’t let the engine sit too long

3.  don’t use it in cold climates

I have signed up for the Cummins Quick serve website, but haven’t been able to enter all the coach info they need yet, so I cannot get any further.   I will definitely check out the service bulletin someone mentioned on the forum.


What are your thoughts on bio diesel?  



Or do you just pump diesel fuel, never knowing exactly what you’re pumping  like one of the commenters said?  Do you avoid it?   Have you filled up with ULSD lately?   In which state?

Do you carry extra fuel filters?

Since, it appears here in Florida they will no longer be selling ULSD, I guess we’ll be forced to use bio.  There may be some small service stations that sell ULSD (like the one near Sunshine Key), but we tend to avoid these stations for two reasons.  One is they are more difficult to get into and two, we worry that the fuel sits too long and may have condensation in it or contaminated.

We’re debating whether to go ahead and change our fuel filters before we leave here, or wait until we’ve run more bio diesel and do them back in Tampa.


  1. I have a CAT diesel, which is rated to use no more than 5% biodiesel. I have found diesel pumps that label the between 5% and 20% biodiesel on them, so you never know what you are getting.

    My personal experience has been that twice now I've had to change both my primary and secondary fuel filters because the biodiesel clogged them up, and my engine started missing.

    Before the biodiesel, I changed my filters annually. Now I change them at least twice a year. I also try to fill up at no less than 1/2 tank of fuel so any biodiesel will be somewhat diluted. I also use a fuel supplement that I pick up at Walmart every second tankful. I carry two compete sets of fuel filters with me, plus an extra fuel filter for the generator.

    If I can avoid biodiesel, I will. It's not a good thing in my engine thus far. I have not seen an increase in power or the engine running smoother when I have to use it.

    If your engine is running fine, I would not change the filters unless there becomes a noticeable difference in the engine's performance. Filters are expensive.

    Good post, you certainly did a lot of research. :c)

  2. Thanks Paul. We'll try to avoid bio diesel as well, but it looks like that's becoming impossible here in Florida.

    What kind of fuel supplement do you use?

    1. It's called Power Kleen, it's in the Walmart automotive section. There are two kinds, one in a silver plastic bottle, and one in a white plstic bottle. I use the silver bottle. It's good to treat up to 100 gallons/bottle. I use it every other tank fill, adjusting for how much fuel I put in at a time (i.e. put in 50 gallons, use 1/2 bottle).

      Around $8 a bottle. Gives me peace of mind and I call it cheap insurance.

  3. Very informative. And here we didn't even know this problem existed. Wow. You opened our eyes today.

  4. I didn't know about this either. I thought you had to midify your engine in some way to use bio diesel. Most of the diesel pumps in CA are marked something like diesel #2. We are a long way from Florida, but hope to get there one day. Please continue to post about this so we can learn more about it. We do carry a spare fuel filter. I read about doing that early on and insisted Craig get one.

  5. Well, this got me curious. Our MoHo runs on gasoline, but my daughter is a trucker so I just texted her and asked what they do with their truck. They own it, so of course maintenance is a big issue. We will see what she says. I know they fuel up at Flying J and Pilot and Love and TA.

  6. We don't pay any attention to it. But carrying fuel filters sounds like a very good idea.

  7. I think I'm glad Winnona just drinks gas. You really provided some great information here Karen.

  8. Glad I ran across this post. We are currently in cold weather and the flying J's had ULSD in our area. We'll keep an eye on this as we travel about. Hubby will pick up extra filters and Power Kleen for our maintenance kit.


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