To fill or not fill diesel for winter

[davenpom]

I hear and read where people say to fill the tanks up before winter storage and others say never to.

We have a 29 with a 120 gal tank and a 30 gal tank.

I'm told if I don't fill up, that leads to condensation in the tank and problems down the road.

Then others tell me that diesel won't be very good after sitting for 9 months.

Some people tell me to use the diesel additive and others tell me this is a gimmick and doesn't work with diesel.

Thanks
Mark

 

[Todd]

It does not matter what you do. I have a lot of diesel equipment and all I do, regarding fuel, is nothing. I leave it with whats in the tank. The chance of significant condensation is slight. Some marinas don,t like to lift boats and store them on jack stands with full fuel because of the weight. The fuel will stay fine for the winter without any additives.

In the spring check your water separator a couple of times and drain it if you need to but I bet you don,t.

 

[mspaugy]

Best to keep it full and maintain your filter/separator system

 

[trailertrawlerkismet]

The Yanmar manual states to either drain the tank or fill the tank to avoid condensation. As it seems to be easier to fill then empty I've always filled my tanks between 3/4 and full. Condensation can cause alge growth that can be problematic to clean out so based on that alone one or the other seems best, just based on what Yanmar states.

Jim

 

[knotflying]

I keep mine topped off and have never had a problem. I use no additive other than FPPF Marine Formula Fuel treatment at every fuel fill. This was recommended by Mack Boring the Yanmar distributor in the Northeast. Never had a fuel issue, knock wood.

 

[baz]

In warm climates does condensation in partially filled tank occur ?

Re: http://www.yachtsurvey.com/myth_of_condensation_in_fuel_tanks.htm

 

[knotflying]

I am not a scientist, but whenever you have moisture in the air when the air starts to cool the moisture will condense. Hence if you have a partially full tank and then a temperature change occurs moisture in the air in the tank will condense and cause water to form in the fuel. Same as a window pane in your house in the winter; when the warm moist air comes up against the cold window you see moisture form on the inside of the window. Imagine that being the inside of your tank. Where do you think that moisture will go as it drips down the side of your tank wall? Full tank, no air, no moisture can occur with no air. This makes sense to me.

 

[Todd]

The difference is that you have a lot of air circulating in a room comming in contact with that cold window. Not much air circulating in a closed tank. If the weight is not an issue it will not hurt to fill the tank and is what most will recomend to be on the safe side. My practical experience with equipment, fity + years of seasonal farm equipment, is just turn it off and start it in the spring. Checking for water of corse but I can not remember the last time I found any.

 

[knotflying]

I’m not questioning your success with tanks full or half empty on your farm equipment, but I disagree that limited air circulation limits the moisture in the air. The vent line sucks outside air in when you are burning fuel as it lets air out when filling the tank and on a hot and humid day that moist air is flowing into your tank. I still think if it is possible to keep the tank full you are safer than half empty.

 

[baz]

We keep our boat in a covered slip all year round. Our location is Edmonds WA. Temps rarely fall to freezing or below for extended times and humidity isn't a problem in my PNW area.

Whenever I leave the boat in the slip I plug in a de-humidifier device (Air Dryer with Fan, Dehumidifier from West Marine). I'm wondering if this helps keeping the air surrounding the fuel tank warmer than it would be otherwise. I assume the temp of the fuel will be similar to the water temperature if the boat is left without the Air Dryer ON.

I'm a little puzzled about the fuel tank moisture issue that people have. First, it's not possible to always have the fuel tank full (for obvious reasons) if it gets used. Surely then, if the moisture was to be a problem then it would surface quite frequently as the fuel gets used.

No matter, filling the tank for extended winter storage can't do any harm other than emptying the wallet. :roll: