Quality Diesel Fuel, and additives

I've been a diesel mechanic for all of about three months now since I purchased my boat. I've got a ton to learn but one thing that seems to be of great importance is feeding your engine quality diesel and the taking care of your overall fuel system. The previous owner was bullish on the use of Startron Diesel Enzyme Treatment at each fueling. Doing the research, I can't find any reason not to continue using it, and I did use it when I fueled the boat on the first (and only to this point) occasion. Reading through the product descriptions for Startron though I don't see any reference to it being an anti-microbial. Should I be adding an anti-microbial in addition to the Startron? On the one occasion I fueled up, I purportedly purchased, ValvTect Premium Diesel from the fuel dock I pulled up to. This diesel reportedly does have an anti-microbial in its mix.

I'm also curious how particular are you folks are with putting a particular diesel product into your fuel tank. My boat is currently in Puget Sound, are most of the marinas/fuel docks in a region selling effectively the same product? I think I understand that there can be a relatively large content difference in the ethanol levels of different blends but is that more regional of can that really vary from fuel dock to fuel dock.

I appreciate the replies! Note that the engines I'm running are older, Volvo Penta TAMD 40s with 3K- hours.

I asked a similar question a while ago and never really got to a consensus. Lots of opinions and everyone that does treat fuel has their own favorite. Valvtect does have include a biocide, more details here.

https://www.valvtect.com/markets/marine-fuels/commercial/valvtect-marine-diesel/

ValvTect is pretty responsive to email, so feel free to ask them any questions. I've decided to always buy ValvTect because it doesn't seem any more expensive where I am, and is allegedly pre-treated. It's also stabilized, but when I asked ValvTect they recommended adding some additional BioGuard for winter layup. During the summer I don't plan to add additional treatment, or if I do, I will add at a reduced concentration.

Hi, link to a very interesting test on the subject. Startron diesel is good but not the best by this test. I actually used it during the winter storage and after months of standing the diesel is fresh.

https://www.pbo.co.uk/gear/12-diesel-bug-treatments-tested-43353


NBs

You mention that your boat is older, but new to you. From that I can assume that you don't have an adequate history of the conditions in which your boat was kept. That is common, as most of us purchase a boat without an adequate history.
My own boat had a history, so I knew most of its usage and storage prior to my own purchase. That purchase took place in 1994, so I know its history in all of its glory since then.
One thing that has changed dramatically over those years is the quality and consistency of the fuel. My boat is located in SW BC, so its fuel is not that different from what you in Puget Sound can get. That dramatic change follows the reduction of Sulphur content. In order to reduce sulphur, the refining process removes all of the dirt and water that formerly came into our tanks with the fuel, so unless you fill up at a very low volume source, you won't be introducing any water. Check your Racor filters for water. If yours are anything like mine you won't find any. Without water, there is no fuel/water interface, so nothing for a biocide to kill.
In the first several years that I owned this boat, I changed my Racors at least once per year, sometimes more often. Now, using only the very clean, very low Sulphur content fuel, my Racors go 4+years, my secondaries 3xthat.
I recently had to clean out one of my tanks, in order to do a repair. That inspection revealed the amount of water and other gunk in the tank after 41 years. Zero water, no evidence of any bio or water related deposits. Only some asphalt goo, and not much of that. Of course, I have no previous tank inspections so I don't know how much of that goo arrived in older, higher Sulphur content fuel and how much in recent times. I would expect that if I inspect in a few years, the amount of goo on the tank floor will not have increased.
All of this is to say that you probably don't have anything to be concerned about, especially if you continue to keep your boat where there is a good, clean fuel supply.

Ethanol shouldn't be present, unless you are buying gasoline.
In diesel, especially in California, there may be Biodiesel. Here, not so much.

ryastu: I was also a user of the Startron additive and never had any fuel problem.
I would avoid using any biocide unless you think something is growing in the fuel.
Think of it as a medicine to treat an infection. The ideal treatment is no water.

koliver: I think the sulfur is removed during refining so no dirt or water in it yet.
That usually happens in aging, leaking storage tanks and maybe in tanker ships.

The could be some ethanol contamination in diesel if stored or shipped in tanks
also used for gasoline. I would hope it would be a tiny percentage, though.

KnotYet said:

r
koliver: I think the sulfur is removed during refining so no dirt or water in it yet.
That usually happens in aging, leaking storage tanks and maybe in tanker ships.

Click to expand...

Do you think it is just coincidence that my Racors suddenly got cleaner when they took out the sulphur?

koliver said:

Do you think it is just coincidence that my Racors suddenly got cleaner when they took out the sulphur?

Click to expand...

Yes

I think the very best additive is using the boat. Your engine will have a return line so running it will filter and polish your complete tank. Using fuel and replacing should keep everything in check. I have had 15 years of diesel boats and never added anything to the fuel. Your location may yield different results.

I don't use anything regularily.

Turn the fuel over and a lot of problems will not show up.
Be carefull about your vendor, that they move lots of fuel and have lots of customer. Ask your neighbours.

Maintain the fuel filler deck fitting. The cap should have O rings. O rings kept in good shape and replaced every few years. , Lightly grease the threads and O ring. That will help keep water out of the tank.

Check the tank vent fittings, that they are oriented properly. THe skin fitting should point backwards on a down angle so no rain or spray can enter. The vent hose to the tank should actually rise above the skin fitting before it turns to the tank. Best done with some 90o elbows.

Keep the water out and you won't get microbial contamination. THey NEED the water and use the fuel as food. Without the water there is no where for them to live.

Buy your fuel where commercial boats fuel. They won't put up with bad fuel. Fuel docks with lots of customers turn their fuel over faster and has fresh additives. Additives go bad with time.

Where you buy your fuel look at the pump. Most have a filter on the side or at the tank. Most have a date. Sometimes it will surprise you.
The fuel today is crap. If your fuel sits use a good additive, especially in cold climates. I grew up using diesel formulated for stability, good combustion, and lubricity for the pump and injectors. All of than is gone with the current fuel.

Time to time I would use Power Service both blends white (winter) and grey bottle (summer) in my commercial diesels. Mostly for antigel and the added luberciticy. Then again up north there was number 1 diesel. With blends of kerosene round 40/60 to diesel. With over a million miles with many motors I think I used addatives maybe 1/16 of a time. I lean either way every now and then ill add a splash into the system.

In the end most fuel from a good source is good enough for the motor as is. If it was not then a lot of fuel/oil companies would not be in business. Use addatives if your fuel has a problem. Then solve the problem.

koliver said:

Do you think it is just coincidence that my Racors suddenly got cleaner when they took out the sulphur?

Click to expand...

Keith
As lower S diesel fuels entered the market place a few decades ago large fleet commercial users indeed noticed less crud building up in the fuel filters. Not only was that a noticeable happening but in large underground mines where Diesel engines were used the Donaldson exhaust filters saw a cleaner exhaust as well with less "soot" build up and less measurable atmospheric particulate matter.

Then as lower S fuels became commonplace worldwide engine manufacturers raised their oil change intervals in fact providing charts showing S Vs oil change hours. For instance my nearly two decade old manual has a Cat recommendation of 400 hours for intervals using diesel with less than 10 PPM and as memory (foggy) serves me 200 hours for S levels escalating above many 100s PPM.

Commercial users turning over millions of gallons of diesel per year found tank farms with less crud in their filtering and centrifuge systems as well as lower S fuels entered the market place. Today's diesel tank farms, not anecdotal, are the recipients of not only the benefits of cleaner and lower S fuels but also diesel fuels exhibiting less moisture and another dozen types of trash and elements.

My boat tanks, well into their second decade, are very clean like yours. My diesel fuel filters showed crud at the initial change likely due to Chinese high S fuel from the initial fuel in all four tanks. Each filter change thereafter the filters have been pristine, again like yours. Only possible degradation of the elements provides me a reason to change the Racors.

I'm into my sixth decade of monitoring diesel fuel filters from a variety of standpoints. Yes, your noticeably clean filters are due to lower S and better refining procedures.

BTW, I well remember dirty fuel at Mexican docks from half a century ago, the Baja filter was well named. And the Mason jar test looking for water and if found triggering a lower valve on the fuel tanks to assist in ridding the tanks of water hose water.

Fuel Additive

You might want to review the Valvetech Additives to see if it has the the missing ingredients you mentioned.

I'm in the "no additives" camp. On Sweetwater, the Swan 57 on which we circumnavigated, Fintry, and now Morning Light, there have always been three filtrations -- a single filter going into the day tank, a pair in parallel between the day tank and the engine, and the on-engine filter.


For most of the last twenty years my fuel has come from Harbor Fuels in Boston, which does 15,000 gallons a day in non-Covid summers, but going around the world we couldn't always choose our vendor -- on one load the first filter lasted only ten hours. Except for that and few other short filter lives, we've not had any problems.


Jim

Arc said:

I think the very best additive is using the boat. Your engine will have a return line so running it will filter and polish your complete tank. Using fuel and replacing should keep everything in check. I have had 15 years of diesel boats and never added anything to the fuel. Your location may yield different results.

Click to expand...

Running and return will NOT polish fuel on all diesels; to wit, Lehman 120s return ounces per hour, if that.

koliver said:

Do you think it is just coincidence that my Racors suddenly got cleaner when they took out the sulphur?

Click to expand...

It wasn't the removing of the sulphur. It was an added requirement for more filtering before delivery to the retail locations.