Recommissioning the Fuel System - Should I Mix New Gas with Old?

[Chotu]

Here is how much fuel I have in each tank. These are each 50 gallon tanks x3.

Looks like 5-6 gallons left in each of the lower ones and 10-15 gallons in the one on the left with the higher level.

Fuel is marine non-ethanol. 4-5 years old at this point.

Brand new fuel pump, great running carbureted new generators, really expensive EFI outboards. Wel, expensive parts anyway.

What’s the plan?

Mix new gas with old and run though carbureted generators?

Dispose of all fuel I can possibly pump out?

[tkeithlu]

5-6 years? Just about everything volatile in it is gone. Gas that is 6 months old goes in my utility truck for immediate burning. If you've got a way to get rid of it, do, if not, dilute the hell out of it with fresh stuff.

[rslifkin]

Pull a sample from the bottom of each tank. Confirm no water in the tanks. If no water, look at and smell the fuel that comes out. If it's still recognizable as fuel, then I'd fill the tanks up with fresh high octane gas and run it. If there's water or the fuel smells like varnish, then it's time to empty the tanks and figure out disposal of the old fuel.


Personally, I mix stabilizer into any gas I'm not sure I'll burn within a month. I've burned stabilized year old gas many times without issue (both ethanol and non) and I've burned 18 month old gas a couple of times (definitely non ethanol, not sure I've ever gone that long with ethanol). After a few years, it'll depend a lot on how well vented the tanks were. The better sealed they were, the more chance you have of the fuel being usable.

[Chotu]

I don’t know how I failed to put this in the post.

I used Stabil marine stabilizer when it was stored.

I think a lot of the volatile stuff is out of it, because it comes right through the gas tanks. Very annoying. But gas tanks are permeable these days.

I really don’t feel like pulling out samples, but I guess that’s the way to go. I was hoping for some magic bullet. Ha ha like maybe I could just fill them the very top with new gasoline.

[rslifkin]

Originally Posted by Chotu

I don’t know how I failed to put this in the post.

I used Stabil marine stabilizer when it was stored.

I think a lot of the volatile stuff is out of it, because it comes right through the gas tanks. Very annoying. But gas tanks are permeable these days.

I really don’t feel like pulling out samples, but I guess that’s the way to go. I was hoping for some magic bullet. Ha ha like maybe I could just fill them the very top with new gasoline.

You very well might be able to just fill them up, but it depends on just what's in there. If the fuel is still fuel-like and not full of water, it'll likely be fine. But if it's really bad or there's water in there, you'd want to know that before adding more fuel.

[Chotu]

Ok! I’ll go this route and pump out some fuel to see.

I wish I knew this varnish smell. I feel like all older has gets a murky color to it and smells like varnish, but it usually runs ok.

I’ll put it in a glass jar next to brand new has and take a pic to get the internet’s opinion.

[psk125]

For perhaps 30 gallons of fuel - worth maybe $90 or less - you are going to risk ruining your new generators and expensive EFi outboards? Clint Eastwood has a question for you : Are you feeling lucky? Tkeithlu has the right idea - mix it in with new fuel and use it in a big utility truck or maybe a lawnmower you don't care about.

[Chotu]

Originally Posted by psk125

For perhaps 30 gallons of fuel - worth maybe $90 or less - you are going to risk ruining your new generators and expensive EFi outboards? Clint Eastwood has a question for you : Are you feeling lucky? Tkeithlu has the right idea - mix it in with new fuel and use it in a big utility truck or maybe a lawnmower you don't care about.

Hell no. That’s why I’m asking what to do.

I feel VERY unlucky when it comes to boat stuff. Ha ha.

I want to do what is best to protect the generators and outboards.m

I own nothing else powered by gasoline at all. Just generators and outboards. There is nowhere to burn it up.

[sailingchiro]

Put in all new fresh fuel. It will save you alot of headaches. Try old fuel in lawnmower.

[Scubaseas]

4-5 years old? I wouldn't use it even with Stabil if you can avoid it. Put it in a truck or some other gas guzzler. Or most waste oil recyclers will take it. When you do fill up consider purging the fuel lines at the motors so you are not putting any 4-5 year old fuel that was left in the piping into the motors.

Stabil says 2 years max on storage of treated gasoline.

If you can inspect the insides of the tanks looking for sludge or gummy deposits. I've seen many a fuel tank that had a layer of varnish from sitting years that came loose when fresh fuel was added. Also keep an eye on your filters as they may clog up quickly. Or not.

For fuel injected engines it's not worth the risk of screwing up the injectors (about $120 each). Carbureted engines you could clean the jets with a jet brush or drill but I'm sure there are plenty of other projects to use your time on.

[Lepke]

If you decide to dilute and use the old gas, add a good fuel conditioner. The additives included achieve more complete combustion.
I would use either Archoil 6400 or 6200 at a 2 or 3x rate. Available online.

[Chotu]

Looks like there are a few different opinions. Like most things. I think I’m going to err on the side of caution. I’m petrified of screwing up my engines and generators. They are working nicely right now. So, I’m going to have to dispose of this gasoline somehow. Oil recycler? That’s the way?

No lawnmower, no lawn, no house, no land, diesel truck until the boat is done. I’m a boat guy. I don’t have all that land stuff

[Chotu]

Definitely, without a doubt, the fuel lines will be completely purged before i attempt to use them.

Originally Posted by Scubaseas

4-5 years old? I wouldn't use it even with Stabil if you can avoid it. Put it in a truck or some other gas guzzler. Or most waste oil recyclers will take it. When you do fill up consider purging the fuel lines at the motors so you are not putting any 4-5 year old fuel that was left in the piping into the motors.

Stabil says 2 years max on storage of treated gasoline.

If you can inspect the insides of the tanks looking for sludge or gummy deposits. I've seen many a fuel tank that had a layer of varnish from sitting years that came loose when fresh fuel was added. Also keep an eye on your filters as they may clog up quickly. Or not.

For fuel injected engines it's not worth the risk of screwing up the injectors (about $120 each). Carbureted engines you could clean the jets with a jet brush or drill but I'm sure there are plenty of other projects to use your time on.

[Chotu]

Originally Posted by Lepke

If you decide to dilute and use the old gas, add a good fuel conditioner. The additives included achieve more complete combustion.
I would use either Archoil 6400 or 6200 at a 2 or 3x rate. Available online.

Looking up this Archoil 6400 product and it appears to only be for diesel

[Scubaseas]

Originally Posted by Chotu

Looks like there are a few different opinions. Like most things. I think I’m going to err on the side of caution. I’m petrified of screwing up my engines and generators. They are working nicely right now. So, I’m going to have to dispose of this gasoline somehow. Oil recycler? That’s the way?

No lawnmower, no lawn, no house, no land, diesel truck until the boat is done. I’m a boat guy. I don’t have all that land stuff

Waste oil recyclers, municipal hazardous waste facilities, busy auto repair shops, any power boater with a gas guzzler may all take it off your hands. Call first.

You could dilute what you have with fresh gas and additive but if you can get rid of the old fuel I would go that route.

Add a -G to the archoil part number.