Mixing fresh and stored diesel?

[Kings Gambit]

I recently mixed stored diesel 1:1.5, approximately, with fresh for a trip to Catalina. Motored over; nothing bad happened that I could detect. I’ve been wishing to use the stored stuff which I bought during the hype over fuel availability a couple of years ago. Yes, stored in containers in my garage for about two years. I wonder about claims that the shelf life of diesel is only a few months, and that it requires maintenance. Of course, I inspected it for color and turbidity before using. It looked and smelled normal. It’s in there and it seems fine. Is there any experience having done this? I always question the “on-line experts” with websites who nix such ideas, probably not having had direct experience. I sometimes wonder what these guys really know, versus passing along what “everybody knows.”

 

[dlochner]

Gasoline goes bad quickly, diesel not so much. I’ve used diesel that 2 or more years old without any issue.

 

[Don S/V ILLusion]

If you believe the US Navy, you might want to read their opinion.

There are links in this link which can lead you to the various studies:

https://www.wpowerproducts.com/blog/generator-engine-fuels/how-long-can-you-store-diesel/

 

[Kings Gambit]

If you believe the US Navy, you might want to read their opinion.

There are links in this link which can lead you to the various studies:

https://www.wpowerproducts.com/blog/generator-engine-fuels/how-long-can-you-store-diesel/

Thanks. I do remember seeing this report (among others) which led me to inspect a sample that sat for two days before I mixed the stored fuel with the fresher stuff in the tank. True, I would not see microorganisms but I was most concerned about clogging the filters with suspended particulates, etc. I’m changing out my two fuel filters (30 and 2 microns) this week, which have not been changed “on schedule.” Interesting that the report mentioned 1.5 to 2 yr of storage as more or less “passable.” I think mine has been stored a bit longer than that but less than 3 yr; it’s written down somewhere. I’m feeling better about using it up.

 

[jssailem]

Great information @Don S/V ILLusion

On a practical side, being the penny pincher I am, I inherited (in my boat purchase) 2 tanks of diesel in 2015 from unknown sources, age, and quantity. I was not prepared to toss it as the price per gallon was in the neighborhood of, so I added 35 gallons and consu $5 USD a gallonmed the fuel over the next couple of years.

There was microbial growth and water in the tanks. I addressed this with a two-pronged attack. I installed a Racor 500 filter housing and bought a supply of filters. I shocked the tank with additives designed to kill the "diesel bugs," changed filters frequently, and added more fuel as needed with additives. Cruising over the past seven years consumed the original fuel.

These last 22 months, during the engine rebuild, the fuel in the tanks has likely developed some contaminates. Once the rest of my boat refurbishing is complete (which includes the installation of my new filter systems), I intend to utilize the polishing capabilities of the system, inspect and treat fuel in the tanks, and filter as necessary.

I've written about fuel issues here in SBO and solutions I employed.

Here is what new my primary fuel filter system looks like.

 

[Kings Gambit]

Because I like having diesel fuel directly on hand (i.e., stored), I’ll probably start a rotation. Keep 20 gallons at home for up to 1.5 to 2 yr. Then swap it out for fresh diesel as needed. Sometimes we need to tank up b/f the fuel dock opens and could not get to it the night before. I don’t like delaying departure awaiting fuel service.

 

[jssailem]

I suspect you will be just fine with the actions you have taken. Additives can improve the lubricity lost as fuel ages and clean up any "diesel bugs" that are floating in the tank. A good primary filter will capture the critters and waste. Just be sure to check your filter and empty any water that has accumulated in the fuel.

 

[Ralph Johnstone]

There are links in this link which can lead you to the various studies:

Interesting is all I can say.

Here is an analysis of fuel taken from a ten year old plastic, 2,500 liter, underground tank which had not received new fuel since it was installed in 2004. We had added Biobor biocide early on and were told the generator was test run by others once a month for an hour. Fuel was tested in 2014.

We took the attitude that if the fuel was properly cared for, keep testing annually until we were told it was NOT fit for future use.

 

[jssailem]

So maybe my simple, naive approach did not destroy my engine.

 

[dlochner]

So the take home message is old diesel is probably OK if it was taken care of in the beginning with the usual recommendations, keep it dry, use a biocide (Biobar JF), and an additive that helps to remove water.

 

[Kings Gambit]

I just put the last couple of gallons of the old diesel fuel in my tank after having burned the rest of it in my Yanmar on a days-long cruise over a couple of hundred miles last summer. Motored most of the way. It ran fine.