Fuel additives? Yes or no

[Delray]

I have twin 490hp Yanmar Diesel engines. Should I use fuel additives or not?
If you should use them, why isn't the fuel pre treated?

[Calif.Ted]

Some fuel does have additives, the fuel dock I use has Valvtech diesel from the pump.
ValvTect - Valvtect Marine Diesel

[sailorboy1]

Originally Posted by Calif.Ted

Some fuel does have additives, the fuel dock I use has Valvtech diesel from the pump.
ValvTect - Valvtect Marine Diesel

I second this

but when in doubt add some, like a biocide prior to layup

[Snore]

As a sailor with a 24 gallon tanks, I use additives. But then again I add fuel every 4-6 MONTHS. And burn a wats under 1/4 GPH.

With twin 490’s you burn the equivalent of my tank in 2 hours or less. Assuming the boat is run regularly, I don’t see a need for biocides. Also with the size of your tanks, it will take a lot of biocide to treat the tanks.

It may be more prudent to add a fuel polishing system.

[S/V Illusion]

Cetane booster is useful. As to other additives, myths die hard. Diesel is refined and all the additives for anything people worry about has already been added.

Just keep water out and you are fine.

[NYSail]

Originally Posted by S/V Illusion

Cetane booster is useful. As to other additives, myths die hard. Diesel is refined and all the additives for anything people worry about has already been added.

Just keep water out and you are fine.

My thoughts exactly, don’t let fuel sit in tank..... only put in what you need plus safety amount. I regularly keep 1/4 or less.

[Shenandoah52]

Another vote for Cetane booster. I just ran some 5 year old diesel in my engine and because I've periodically added Cetane booster to the stored fuel it worked for me and the diesel ran fine with it. YMMV.

[Simi 60]

Never use it.
We have 7000 litre tanks that are rarely more than half full.
Had 10 year old diesel in her when we got her.
Zero water and zero crud.

[redneckrob]

Originally Posted by S/V Illusion

Cetane booster is useful. As to other additives, myths die hard. Diesel is refined and all the additives for anything people worry about has already been added.

Just keep water out and you are fine.

That's certainly true for "performance enhancers" and the like. Definitely not true for algecides, biocides, anti-icing and the like. It was a requirement in the Coast Guard that we had Prist in all our jet fuel for example, and always carried several cans around because civilian airport jet fuel usually didn't come with an icing inhibitor added. That requirement wasn't based on a myth!

[S/V Illusion]

Originally Posted by redneckrob

That's certainly true for "performance enhancers" and the like. Definitely not true for algecides, biocides, anti-icing and the like. It was a requirement in the Coast Guard that we had Prist in all our jet fuel for example, and always carried several cans around because civilian airport jet fuel usually didn't come with an icing inhibitor added. That requirement wasn't based on a myth!

What does jet fuel have to do with the subject?

Ice isn’t a problem at sea level on a boat unless you begin the arctic cruise with water in the fuel.

[crankysailor]

Originally Posted by NYSail

My thoughts exactly, don’t let fuel sit in tank..... only put in what you need plus safety amount. I regularly keep 1/4 or less.

isn't commonly accepted that keeping the tanks full is best when not using the boat for a long period to avoid condensation etc?

I was wondering about this actually..I bought a boat recently and it had a 4/5 full tank..that diesel has been probably sitting there for years now as the previous owner wasn't moving the boat a lot I get the feeling. Wouldn't at some point be best to throw that away? (at 250 liters not chump change with european fuel prices!!).. does Diesel get "old"?.. isn't this why one should add a biocide or some other additive, when keeping the stuff around for longer than the refinery planned for for most people?

[redneckrob]

Originally Posted by S/V Illusion

What does jet fuel have to do with the subject?

Ice isn’t a problem at sea level on a boat unless you begin the arctic cruise with water in the fuel.

Well first off jet fuel and diesel are the same fuel. In fact, pro tip for you, when I'd deployed on cutters in the Coast Guard and we'd have to get fuel in Central America the cutter would order jet fuel and use it for the main diesel engines because you were far more likely to get crappy fuel if you ordered diesel.
Second, it's a perfect example that it's simply not true that the refiner will put in any additives that might be needed for your specific application, whether that's an icing inhibitor for jet fuel or an algicide or biocide that's needed if your fuel sits for a long time and not needed by the vast majority of diesel users who run through the fuel in their tanks in a matter of days or weeks.
Just for future reference, I (and many others) like to make use of examples, references, and similarities, so taking our words absolutely literally is likely to lead to confusion at best. Perhaps if an absoutely literal interpretation of someones post doesn't make sense it might be useful to ask ones self if this is an example, a metaphor or the like rather than assuming they're a moron advocating that everyone put Prist in sailboat diesel in the Caribbean to prevent freezing in fuel lines (although I suppose it wouldn't be a bad idea if you live anywhere cold).

[Shenandoah52]

Originally Posted by crankysailor

I bought a boat recently and it had a 4/5 full tank..that diesel has been probably sitting there for years now as the previous owner wasn't moving the boat a lot I get the feeling. Wouldn't at some point be best to throw that away? (at 250 liters not chump change with european fuel prices!!).. does Diesel get "old"?

A couple posts up I mentioned 5 year old fuel being still good and Simi 60 mentioned 10 year old fuel. There is a "we resurrected an old Peterbuilt" or something along those lines on YT that went viral and I can't recall correctly without watching it again but I think the fuel in that truck was over 20 years old. Don't be too quick to get rid of that diesel, it could still be useable.

[sail sfbay]

"Should I use fuel additives or not?"
Vote for diesel fuel Starbright Star Tron treatment to disperses moisture to help prevent bacteria without the use of a biocide. I use this product. Alternatively, use a biocide such as Bio Kleen Diesel Fuel Biocide to kill microbes in fuel, including bacteria and fungus to mitigate fuel system of microbial contamination and fuel filter pluggage.

"If you should use them, why isn't the fuel pre treated?" Diesel fuel suppliers do not treat the fuel with a biocide since is no biocide specification and would increase production cost. They do treat the fuel to meet cetane and lubricity specifications depending.

[Dean Paul]

Some comments about fuel additives..Inboard gas, Palmer P60...use about 4 gallons per season.

Each fall I add Phasor 3, Stabil, and Startron. Periodically add lead substitute for valve health. All gasoline added in is non ethanol....fill each fall.

While it seems that many additives are excessive...and they may be cumulative...seems to work for me.

Thoughts?

Dean