What's the score with storage of bio diesel?

[stuhaynes]

I've been told that the new red diesel only has a 'tank' life of about 6 months. Is this true? If it is, is there an additive that can extend it's life or is a tank clean going to be necessary every spring?

 

[rafiki_]

Our marina is using an additive, so not sure how long this extends the life. I also use additives when I fill, soo need to check they are compatible.

Others have used white diesel for some time, and this has included up to 7% bio for several yearas, with no apparent problem.

 

[Assassin]

The issue with bio diesel is that it is actually biodegradeable and breaks down in as little as three weeks, and is hygroscopic to a large extent, which means it absorbs water, these are the main problems.

With normal road diesel we have a bio element averageing 5% bio content, this can be slightly higher or lower, but the normal diesel has a massive additives package as standard, so enhances the life of the bio element. Additives are available, but testing has shown them to have little affect on the life of bio.

The best advice is to run bio if you use the boat regularly, and if you store it for a period, or have a period of inactivity, then put a larger normal diesel content in prior to the inactivity.

 

[Latestarter1]

The issue with bio diesel is that it is actually biodegradeable and breaks down in as little as three weeks, and is hygroscopic to a large extent, which means it absorbs water, these are the main problems.

With normal road diesel we have a bio element averageing 5% bio content, this can be slightly higher or lower, but the normal diesel has a massive additives package as standard, so enhances the life of the bio element. Additives are available, but testing has shown them to have little affect on the life of bio.

The best advice is to run bio if you use the boat regularly, and if you store it for a period, or have a period of inactivity, then put a larger normal diesel content in prior to the inactivity.

Good advice, however 'real world' FAME content appears to be more in the order of 3% according to fuel suppliers which is good news.

Going back to original subject this is not really a bio diesel subject, more just a a diesel/gas oil subject. Firstly fuel starts to degrade the moment it leaves the refiners.

Fuel suppliers to MOD take the view that ultimate life of diesel gas/oil after leaving refinery in 12 months if ambient storage temperature is no higher than 20C. Over 30C cuts storage life to 6 months.

As diesel gets older a fine sediment and gum forms in the diesel brought about by the reaction of diesel components with oxygen from the air. The gums and sediments do not burn in the engine very well and can lead to carbon and soot deposits on injectors and other combustion surfaces.

Other factors can accelerate aging process, Contact with zinc, copper or metal alloys containing them (brass). These metals will quickly react with diesel fuel to form unstable compounds. Water content is another factor, fungal growth creates vicious organic acids which cause seal failure and can actually attack the tank itself.

Maintenance doses of Fungicides/Biocides. unlke 'kill' doses are effective but no more so than regular water draining. Remember fuel treatments aimed fungal/bio contamination do not have any effect on oxidation processes.

Take Assasin's advice use the darn stuff having fun instead of saddo's like me who seem to spend their life reading data sheets!