Chevron: Everything you need to know about Marine fuels

The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
Without downloading them what is there to understand and why do you need additives?
I thought we simply filled the tank with diesel and burned it.
 
Last edited:
Interesting to see, just like jet fuel (which is probably virtually the same thing) marine diesel comes from the refinery with water already a component. This, of course, in a recreational boat which is not used often or sits for a long time, plus the added moisture from the air, (which is MUCH less than most people think) means that boaters need a method to remove the water that settles out of even the best quality fuel. This is why soft iron tanks and some badly welded stainless tanks will start to corrode internally, eventually.
 
Without downloading them what is their to understand and why do you need additives?
I thought we simply filled the tank with diesel and burned it.


I went through the article with some care, and learned a lot, but it's probably worth rereading it. I'm especially interested in the production of asphaltenes and paraffins that precipitate out of diesel with oxidation and the environmental causes of that process. I am trying to learn about aftermarket additives and whether they are worthwhile here's Chevron's take:

"Aftermarket Additives...

It would be convenient for the user if a finished diesel fuel could satisfy all of his or her requirements without the use of supplemental additives. Although this is usually the case, some users require additional additives because the low-temperature conditions in their region are more severe than those for which the fuel was designed or because of other special circumstances. Other users feel that they will benefit from using a diesel fuel with enhanced properties compared to using regular diesel. Finally, there are users who regard the cost of an additive as cheap insurance for their large investment in equipment.

A large number of aftermarket additive products are available to meet these real or perceived needs. Some are aggressively marketed with testimonials and bold performance claims that seem “too good to be true.” As with any purchase, it is wise to remember the advice, caveat emptor, “let the buyer beware.”

It may be helpful to regard additives as medicine for fuel. Like medicine, they should be prescribed by an expert who has made an effort to diagnose the problem, as well as the underlying causes. Additives should be used in accordance with the recommendations of the engine manufacturer, and the instructions of the additive supplier. Sometimes, indiscriminate use of additives can do more harm than good because of unexpected interactions."

I added Stanadyne early on but stopped using it, because I could not find compelling literature that indicated any benefits.. Based on the above from Chevron, I will probably save my money and not use it.

Other things I've learned: page 35 on blending:

"The refiner really has limited control over the detailed composition of the final diesel blend. It is determined primarily by the composition of the crude oil feed, which is usually selected based on considerations of availability and cost. While the chemical reactions that occur in the conversion processes involve compositional changes, they are not specific enough to allow for much tailoring of the products. Yet, despite these limitations, refineries daily produce large volumes of on-test products."

Another take-away: if you "blend" diesel from different suppliers the resulting mix can become unstable: a refiner blends the diesel to specific compositions etc based on the original crude oil. That blend changes the stability of the fuel:

"Contrary to intuition, two fuels that, by themselves, have good stability may form a less stable blend when they are combined. In this case, each fuel contains some of the precursors needed for the formation of higher molecular weight species. Only when the fuels are mixed are all the precursors available, enabling the conversion to proceed."

"DIESEL FUEL CHEMISTRY Figure 4.2 illustrates a typical carbon number distribution for No. 2-D diesel fuel, and Figure 4.3 shows a typical distillation profile. Diesel fuel is a very complex mixture of thousands of individual compounds, most with carbon numbers between 10 and 22. Most of these compounds are members of the paraffinic, naphthenic, or aromatic class of hydrocarbons; each class has different chemical and physical properties. Different relative proportions of the three classes is one of the factors that make one diesel fuel different from another."

Jim
 
" Different relative proportions of the three classes is one of the factors that make one diesel fuel different from another.""

However the fuel in an area probably comes out the same pipe at the distributor , where it then goes to different land vendors and marinas.

Perhaps the retailers add some majic to make it a "brand" fuel, perhaps not.

To me the most important thing I want in fuel is it to be CLEAN.

It slows down the fueling , but we only hold 200G , so we use a baja filter to be sure the delivery folks did their job.
 
Knowing that I can not always control the quality of fuel supply 100%, I use the following . I try to buy fuel only at high volume reputable dealers. I do not believe in overly large fuel tanks with lots of static fuel on coastal and inland use boats. I rely on a multi stage filtration system with high capacity first line units with vacuum gauges with captive needles. I do not think there is a magic additive and suspect if there was one competitive market pressures would have the brand name fuels using it. It is good to know the detailed chemistry but may be of little practical value.
 

Latest posts

Back
Top Bottom