Any experience with plant-based marine diesel fuel?

Refilled tanks at my usual marina. A couple of weeks later, I learned that the marina had recently changed, with no notice to customers, not only its diesel suppliers but the fundamental nature of the diesel fuel itself. They now sell a plant-based fuel supplied by an unknown company with the advertised name of MY Neste (and I put 250 gals of this stuff on top of 200 gals of conventional diesel.) I searched and found a seemingly large (global) Finnish refinery and plant-based diesel fuel supplier named Neste MY (go figure.) I've asked them to send me the info I need to feel confident that my 30-year old Cat 3208s can run on their plant-based fuel and that seals etc. wouldn't be compromised. No reply after two weeks.

I called my well-regarded local Cat representative, found a technical guy said to be steeped in diesel fuel knowledge. He didn't know anything about plant-based marine diesel fuel compromising marine systems but eased my worry by saying that 3208s are known to be tolerant of fuels, and said that they have proven to run well for years on drain oil!

I've been using plant-based diesel in my 10-year old MBZ diesel SUV with no known damage, but this after doing a fair amount of research. So far, so good but it is a "newer technology car", and certainly not ancient 3208 powered.

What can we all expect with our 3208s (and other older marine diesel engines) with these alternative fuels? (Beware of marina's changing to such alternative fuels without warning) Anyone have relevant experience or technical knowledge to contribute to the Forum?

Research the water absorbing characteristic of "bio-diesel"

My research turns up distinct differences in what is marketed as "plant-based diesel" and more conventional "bio-diesel" sold for years now. "Bio" referring more to recycled cooking oil and the like. Plant-based referring to native grasses, land-based or water-based. These apparently have none, or at least different, downsides from bio-diesel. Both sell for a little less than conventional carbon-based diesel (tax differences?) But I'm an amateur when it comes to this stuff. Looking for more relevant info...anybody?

Bio diesel can act like a solvent. BC Ferries tried 100% bio diesel and had trouble with the fuel cleaning the tank sludge and plugging the fuel filters. One ferry had to be towed in. Last I heard, they went to a less than 50% bio mix. If you maintain clean tanks, it shouldn't be a problem. Possibly a shorter filter life for a few tank fulls.

My plant base diesel knowledge is lacking. What I do know is that diesel is a fuel while bio-diesel is a solvent. Diesel leaves deposits, bio-diesel dissolves those deposits clogging filters and injectors down the line. You need to find out if this plant based diesel is a solvent or a fuel.

If it is used for fuel then it is a fuel.

Most liquids are solvents which dissolve some chemicals. For example - Water. Water dissolves sodium chloride and become seawater.

So the answer to the above question is - petroleum based diesel, bio diesel & plant-based diesel are all both a fuel and contain a solvent. If they didn't contain a solvent, the solids would not dissolve. You'd have lumps of solid sulphur in your diesel.

If your really concerned, hire a pro to pull it. Someone would be willing to take that from you and run their old tractor, etc. Another option, make sure it has similar qualities and take a long trip to burn it all out. Such as lubricity. Biofuels can chew up filters but diesels in general will burn just about anything due to their nature.

AusCan said:

If it is used for fuel then it is a fuel.

Most liquids are solvents which dissolve some chemicals. For example - Water. Water dissolves sodium chloride and become seawater.

So the answer to the above question is - petroleum based diesel, bio diesel & plant-based diesel are all both a fuel and contain a solvent. If they didn't contain a solvent, the solids would not dissolve. You'd have lumps of solid sulphur in your diesel.

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You can argue with the petroleum engineers. They have their classifications and they labeled bio-diesel as a solvent. Next there will be an argument over what is a motor and what is an engine.

Plant based diesel=vegetable oil
For fuel, it comes with several advantages, cleaner burning, bio-degradable and more.
That magic has a price, in this case its stability. It can hold 15to 25x more water than petro diesel. It is a petrie dish for microbes, with water held close to veggie oil (food) due to the polar nature of both. A petro diesel will layer water at the bottom (only); bio its emulsified thruout.

So, that is the price. Don’t store it long, as proven by rusting steel storage tanks, a new problem starting with ULS blends.

I wouldn’t worry about the fuel in your tank, but I would think it worthwhile to continue to do more research. That can be hard. So much of the information out there is going to be based on research from oil companies. Not exactly impartial. Then there are all the “a friends uncle had problems when....” type of reports.

I burned bio-diesel in my Yanmar 56hp diesel in my sailboat. It was cheap and I was a sailor. I didn’t run it 100% but ran it at about 50% with regular diesel. Since I used about 50 gallons of fuel total a year, the 50 gallon drum of bio-diesel lasted a few years.

On my boat, if I was going to go on a longer vacation where I would be burning through a lot of fuel, I would be happy to add 50% bio-diesel to my modern engine. I would not want it sitting in the tank for an extended time. Whether true or not, I would worry about moisture absorption. I wouldn’t worry about cleaning the sludge from the tanks, that what fuel filters are for and the advantage of a duel primary filter setup. In fact, running some bio-diesel through the boat on a yearly 2 week vacation might help keep the fuel system clean.

My opinion is worth less than $0.02.

I am in SoCal at the moment (winter Snowbird) and here, all they sell is 20% bioDiesel. I detect no odor, no difference in price, no change in mileage in my Cummins ISL 400, no effect on filters or other parts.

Sounds like an unwanted ingredient with negative qualities (like diluting the fuel's energy, reducing food supply, damaging engine), as in adding plant-based alcohol to gasoline.

Long term storage and damage to the exhaust system seem to be the problem for M-B.

If forced to fill with over 5% bio content M-B requires the fuel to be used as quickly as possible , and more frequent oil changes.

Most boats do not yet have DEF requirements for their exhaust system , but the problem of the bio gunk "cleaning" an old fuel tank is real, so carry lots of fuel filters!

The solvent nature of plant diesel isn't just a filter problem: it can attack many plastics. This includes seals in the injectors, pumps, hoses, etc. Newer diesels are often built with more modern and more resistant materials, with the expectation of 20% bio, but older diesels can have a lot of problems. Hoses and seals either swell up or dissolve or both.

DDW said:

The solvent nature of plant diesel isn't just a filter problem: it can attack many plastics. This includes seals in the injectors, pumps, hoses, etc. Newer diesels are often built with more modern and more resistant materials, with the expectation of 20% bio, but older diesels can have a lot of problems. Hoses and seals either swell up or dissolve or both.

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I pulled up a materials compatibility chart, looking at veggie oil vs diesel. Not too surprised with the hits that EPDM took, more surprised at steel, iron, polyethylene.