fuel additives

[derekh]

Over the last 4 years I have used a fuel additive to protect my fuel from the dreaded bug. During those years I was concerned by the amount of black dirt building up in the fuel. Each year I annually cleaned the tank and replaced the filters every 30 to 40 hours of use. Last year I made the descision to stop using the additive to see what would happen. Today the Volvo mechanic serviced the engines. he replaced the fuel filters as a precaution. He says they are like new. I now abviously have serious doubts about the use of additives and would be interested to hear your views.

 

[shaqra]

Hi
Dont know about fuel additives but have a read of this about oil additives!
http://www.ford-trucks.com/article/idx/1...A_Negative.html
Regards

 

[jimbaerselman]

By 'bug' I guess you mean bacterial growth in the fuel tank. For this to occur, there must be some water present in the tank - usually arrives there through condensation as the empty bit of the tanks 'breathes' with temperature changes.

The bacteria develop at the water/fuel interface. The sympton is growth of small sheets of black goo - maybe 1cm across. The effect is, if your tank is fairly empty, and you've just been stirring things up, your pre-filter will collect a load of slime.

Cure is frequent pre-filter changes (so it doesn't clog up) or a dose of appropriate diesel anti-bug additive followed by a fuel change or a 'fuel clean' or 'Fuel polish'. It will be very rare that the goo gets beyond the prefilter to muck up the fuel fine filter.

So, yes, if your tank is infected with bacteria, a bacteria killing additive can be useful. Ignore 'performance enhancing' additives. Snake oil. If they worked, the fuel companies would already be using them - there's a lot of competition out there!

 

[TigaWave]

Never used additives and never had a problem. I would consider them if bacterial growth was diagnosed.

I did check my tank visually every 6 Months and change filters every 150-200 hours and used fuel from a wide variety of sources from UK to Trinidad.

If you keep the tanks topped up to reduce moisture there doesn't seem to be a problem, I use a friends yacht that is wintered for 4-5 months, haven't seen a problem with his fuel for the last 4 years.

 

[leadersail]

I also keep my tank full over winter to reduce the condensation risk (we all know how a cold can of coke can condensate ) however the air with in a tank is not exchanged as the breather restricts flow.
The amount of moisture present in 40 gallons of air is unlikely to cause a moisture issue.

The most likely source of water in Tanks is via a poor filler seal, I replace the O-ring every year and tape over the filler cap over winter.

 

[neil_s]

I don't use additives - but my fuel tank has a little drain cock at the bottom. Every autumn, I open it and let about half a pint of fuel out into a jam jar. There is always about 1/2 inch of water in the bottom of the jam jar. This seems like a very small amount but I guess that if I didn't drain it off it would accumulate and provide a medium for bugs to grow.

Neil

 

[pissativlypossed]

I use and swear by Soltron, We had a bad dose of the bug on a previous boat and had the tank drained and cleaned as a result. Started using Soltron in our second boat when new 4 years ago and no issues so far.
Incidently, the marina dose the fuel they sell with Soltron as a matter of routine.

 

[VicS]

[ QUOTE ]
The amount of moisture present in 40 gallons of air is unlikely to cause a moisture issue

[/ QUOTE ] I think you will find that the problem arises because the tank "breathes" as the temperature fluctuates. As the air cools it contracts and air is drawn in from outside, if it cools below the dewpoint, something that is more likely to happen in winter than summer perhaps, water condenses. Because the temperature is constantly fluctuating the air is constantly expanding and contracting, bringing fresh moisture laden air in every time the temperature falls and producing more condensation every time the temperature falls below the dewpoint.

If the air space is kept to the minimum by keeping the tank full then the volume of air, and hence water vapour, entering with each cycle is minimised. The mass of fuel in the tank may also to some extent stabilise the temperature, at least in the short term.

The breather pipe will not restrict the flow but a long breather pipe may act as a bit of a buffer which a usually short filler pipe will not do. You are therefore correct in suggesting that the filler cap seal should be maintained in good order.

It is said not to be such a problem with petrol (gasoline for our transatlantic cousins) tanks because of the high vapour pressure of the petrol.