I'm a bit mixed on additives.  I've tried numerous times to get a straight
and  scientific answer but to no avail.  Some things that are prominent in
my memory are as follows.

Most diesel already has an additive package to prevent bio growth the
question is, "How long does it last?"  The bio-bore bottle states that each
tank should be retreated every 6 months for "maximum protection".  IMO if
you are turning over the tank (completely using and then filling) once or
twice a year then you should be ok.

The growth occurs because of water in the tank and emulsified in the fuel.
Often times people will site a water/fuel interface layer in the tank
similar to when the Italian dressing has say for a while.  The theory goes
that the algae live in the water and eat the fuel.  This can cause the
black goo or a harder particulate to form and hopefully get caught in the
fuel filters.  Additionally, the water is more dense and as such the only
means for effectively removing the water is the use of a low point drain on
the tank. If enough water accumulates (1/4 to 1/2 inch) then you are near
the point where the pickup tube can suck up the water/fuel mix where the
algae have been busy making goo.  Long durations of stagnant fuel
facilitate the depletion of the biocide package which came with the fuel.
These long durations may be followed by significant agitation which breaks
up the goo layer combined with the pitch and heel of the boat again
facilitate the goo being sucked up by the pickup tube.

Poorly placed tank vents.  Poorly installed tank vents.  Degraded tank
vents and hose.  Knock downs.  All can allow water into the tank.

The filter funnel marketing and demonstrations are quite convincing as to
how much water can be emulsified IN the fuel directly from the fuel
station.  The demonstrations are also powerful is proving how well they
remove the water.

There are differing opinions as to whether or not a full tank causes or
prevents condensation from forming in the tank.  Maine Sailor did a pretty
good write up but read the comments too.
http://www.pbase.com/mainecruising/fuel_tankt_condensation

IMO it is better to eliminate/remove/prevent the water than to try to
control growth with an additive.  I'm always hesitant to use additives of
any type since it is no guarantee of improvement and may in some cases
actually be worse.  Lower cetane and lubricity are 2 possible outcomes

Modern diesel is low sulfur.  The sulfur is what was used to increase the
lubricity which is critical to reducing wear on the fuel injectors and HP
pump.  IMO this is a bigger hazard to operation of the engine than bio
growth.  I use an additive from Opti-Lube called XPD.
http://www.dieselplace.com/forum/76-speciality-forums/64-maintenance-fluids/177728-lubricity-additive-study-results.html#/forumsite/20625/topics/177728

It does seem that there is a certain amount of mysticism with all of this.
Some people report no problems after years of not changing filters, sitting
on the hard, partially filled tanks,  etc.  And others seem to be very
particular with regard to fuel system maintenance and yet perpetually
battle goo, debris, clogged filters, etc.

My vote is a using a filter funnel while refueling, adding the opti-lube
XPD, and using as much of the fuel in the tank as possible between fill ups.

As always YMMV

Josh Muckley
S/V Sea Hawk
1989 C&C 37+
Solomons, MD
On Oct 12, 2015 12:39 PM, "Richard N. Bush via CnC-List" <
[email protected]> wrote:

> With apologies for re-raising a previously discussed topic; my boat is a
> 1985 37 with the original Yanmar 3HMF 27 hp; I went for my annual diesel
> fill up and the pumps were out of order; so I had to get diesel from a
> street gas station; although the cost was almost a dollar per gallon
> cheaper, I noted that it was the "green" color rather than the "red" color;
> so my question is do I need to put some type of sulpher additive or
> something along those lines into this fuel? I did motor with it for an
> extended time on Sunday with no adverse effects; in addition to this
> question, what should I use for the upcoming winter layup? many thanks
>
> Richard
> 1985 C&C 37 CB; Ohio River Mi. 584;
>
>
> Richard N. Bush
> 2950 Breckenridge Lane, Suite Nine
> Louisville, Kentucky 40220-1462
> 502-584-7255
>
>
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