diesel stored 2 years with stabilizer and biocide, should I drain and clean tanks?

[chrisr]

suspect a lot has to do with the quality of the fuel in the first place. we had no end of trouble with diesel that was about 2 years old...but it was from indonesia (bali to be specific) so enough said

you don't mention where your fuel was from initially ?

cheers,

[Simi 60]

Originally Posted by chrisr

suspect a lot has to do with the quality of the fuel in the first place. we had no end of trouble with diesel that was about 2 years old...but it was from indonesia (bali to be specific) so enough said

you don't mention where your fuel was from initially ?

cheers,

Various grades there and it's all cheap

Yachties wanting to save a few cents tend to buy solar pumped out of rusty drums and then bleat about fuel quality.

Spend a few cents more and get Pertamax Dex

[Simi 60]

We bought our boat with half empty fuel tanks and 10 year old diesel heavily discoloured red in colour vs gold.

Ran it with zero issues - it was 12 mths before I changed a fuel filter and it was spotless.

5 years later, never used any additives and still running those same filters.
Pull them every year for a look, put them back in.

[Tin Tin]

Fuel tank cleaner works, just replace the primary filters if they start to clog up. Star Tron Tank Cleaner

[Chotu]

Originally Posted by Simi 60

We bought our boat with half empty fuel tanks and 10 year old diesel heavily discoloured red in colour vs gold.

Ran it with zero issues - it was 12 mths before I changed a fuel filter and it was spotless.

5 years later, never used any additives and still running those same filters.
Pull them every year for a look, put them back in.

Where did you buy the boat?

All diesel is red in the States unless it’s used on the road and taxed for road use. They dye it.

[rslifkin]

As others are pointing out, diesel itself is pretty stable, although after enough time it can start to precipitate asphaltenes that can gum up filters. Provided the fuel and tank start out clean, it can be stored for a long time. But if the fuel has any water or grime in it, or the tanks aren't clean, then you'll develop more problems the longer you store it.

[waterman46]

Depends on your previous experience with these motors. Your diesel will be fine, unless the boat has a history of problems with contamination prior to that storage. Actually since you say the engines were run during your absence, you are ahead of many of us who had been away during Covid.

When I got to my boat 21 months after it being run only once during that period, I just changed all the filters and the Racor's looked just a little light tan color as they always do after a year or so. The engine ran fine, started instantly as it always does. I always have used a little biocide with each filling, but nothing added during the storage.

[Arrandir]

Recently one person on CF wondered what to do with the tank. Can be worth to read too.
https://www.cruisersforum.com/forums...ot-262529.html

[s/v Jedi]

If you plan to store diesel for a long time, add Startron enzyme based treatment to it rather than a biocide (instead of killing bacteria, it prevents them).

[purvisgs]

The fill level of the tank when you left it is also something to take into consideration. Best practice is full tanks for long term storage (with whatever flavor of additive you prefer).

A partially empty tank vented to atmosphere with a lot of air space-- can condense/accumulate significant water in some cases. Water will settle out over time to the bottom of the tank of course, and you may be able to get away with just pumping/draining only the bottom inch/es of the tank, or in the more mild cases just extra additive plus dilution with fresh fuel. Whatever approach just ensure you use quality (like racor 5 micron) fuel filter/s with real water separator, with several spare filters on hand.

Water in fuel and the air/diesel boundary is where "algae" and other contamination are able to start to proliferate. Also warmer temps can I believe be a factor. Without any water though, old diesel will last for many years.

[Chotu]

I’m with Jedi on this one.

Find a local clergy person, have them bless the tank, and head out.

[s/v Jedi]

Originally Posted by purvisgs

The fill level of the tank when you left it is also something to take into consideration. Best practice is full tanks for long term storage (with whatever flavor of additive you prefer).

A partially empty tank vented to atmosphere with a lot of air space-- can condense/accumulate significant water in some cases. Water will settle out over time to the bottom of the tank of course, and you may be able to get away with just pumping/draining only the bottom inch/es of the tank, or in the more mild cases just extra additive plus dilution with fresh fuel. Whatever approach just ensure you use quality (like racor 5 micron) fuel filter/s with real water separator, with several spare filters on hand.

Water in fuel and the air/diesel boundary is where "algae" and other contamination are able to start to proliferate. Also warmer temps can I believe be a factor. Without any water though, old diesel will last for many years.

The condensation in a half empty tank turned out to be a myth when tested. Of course I forgot who tested this but the conclusion was that the difference was negligible, not enough to worry about.

The bacteria live in the water/diesel boundary (not air/diesel boundary) and the enzyme treatment prevents this boundary from forming and breaks down bacteria to be burned with the fuel instead of just killing it and clog the filters.

When there is an bacteria infection, then best treatment is a shock treatment of Biobor + shock treatment of Startron.

I believe all this info came from Practical Sailor.

[Minggat]

Fuel polishing isn’t always such a great answer.

A friend lost her boat on the rocks because she trusted fuel polishing.

Just using fuel and changing filters can be futile.

I do not agree that you are ok with what you’ve got. You are flying blind until you take a look.

Get a $30 borescope on Amazon. Take a look and then decide your course of action.

[Simi 60]

Originally Posted by Chotu

Where did you buy the boat?

All diesel is red in the States unless it’s used on the road and taxed for road use. They dye it.

Australia
All diesel here is gold in colour unless it's old and manky.

[Simi 60]

Originally Posted by purvisgs

.

Water in fuel and the air/diesel boundary is where "algae" and other contamination are able to start to proliferate. Also warmer temps can I believe be a factor. Without any water though, old diesel will last for many years.

I'm a firm believer that water is caused by deck fillers and neglected O rings

We have our fillers in the cabin sides, they never see water, but orings are still checked and replaced with spares carried.

We bought her with 3500 litres of old, discoloured diesel in her 7000 litre tanks and she lived in a sub tropical area known for humidity.
Being an ex commercial vessel she has properly designed tanks with a drainage crud sump at the lowest point.
Fuel samples taken showed zero water or any crud.

We have had her for 6 years now
Check the crud sumps every month or 3 and am yet to see anything.

Have never used any additives of any sort
Tanks are rarely ever more than half full.