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Old Gas for Outboards

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Stu Jackson C34
Admiral

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844 Posts

Initially Posted - 08/06/2008 : 19:32:52

In reading the recent "flushing" story, I was reminded of a question I have been wanting to ask this group, who, IMHO, are the true experts on all things outboard.

We have a 1990 Evinrude 2 stroke (don't beat on me, please, I bought it eight years ago at a swap meet sale for our then-new 10'-2" dinghy, and it works great - after some internal electrical repairs).

I've been reading for years about the horrors of keeping and trying to use old gas.

Two weeks ago I bought some new gas in our backup container for a short trip we were taking, but found that there was enough gas (premix) in the 3 gallon transom tank from LAST YEAR so I didn't bother adding any fuel to the dinghy tank.

The old fuel worked fine and the engine started on the fourth pull.

So, help me out here: What's the big story about old fuel not working??? The only thing I ever mixed with the gas was the 2 cycle oil, no stabilizer, etc. Are we dealing with urban myths again?

Stu
1986 C34 #224 "Aquavite"
Cowichan Bay, BC Maple Bay Marina
(formerly San Francisco)
(formerly C25 #2459 "Capricorn Two")

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 08/06/2008 : 20:43:36

Disclaimer: The following opinions are worth less than you're paying for them...

The engine might start and run, but conventional wisdom has it that:
1. Very old gas tends to varnish the carburator, affecting the mixture setting and jets.
2. Gasoline in general, and E-10 gas most especially, loses a signficant amount of its octane over time, causing knocking in some engines. (...probably less of a problem in older 2-strokes.) I've been told that E-10 loses some big number like 30% of its remaining octane per month. While 50-octane gas might be able to make an engine run, it isn't good for it the pistons, valves, and plugs.

The common solution, or compromise if you will, is mixing old gas half-and-half with fresh--or similarly, putting a modest amount into your car's tank with fresh gas. Startron claims to restore old fuel, but I'm dubious about that.

Edited by - Dave Bristle on 08/06/2008 20:45:28

dmpilc
Master Marine Consultant

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USA
4593 Posts

Response Posted - 08/06/2008 : 21:44:08

I just went through this with an emergency generator (regular unleaded not pre-mix gas). The gas was maybe a year old since we had not had any good power failures in a while. When I tried to start it up, I noticed a fairly strong varnish-like smell coming from the exhaust. To make a short story even shorter, I ended up having to replace the carb because of non-use and the old gas. I would suggest not using gas more than 3 months old in your outboard. Pour it into a spare gas container and mix it with your lawn tractor gas or your car's gas (no more than a gallon per tank on the car.)

Edited by - on

stampeder
Master Marine Consultant

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1608 Posts

Response Posted - 08/06/2008 : 22:39:24

I've used two year old gas in my Honda 9.9 without any issues. However, I am told by some that I dodged a bullet and by others, that gasoline will maintain sufficient octane for at least six months, I heard from a chemist that octane in gas should be good for 18-24months. A Honda rep told me that gas in their engines should not exceed 3 months old, however - if it does they recomend an octane booster.
All that said: I have a six gallon gas tank that I rarely fill more than half full because I want fresh gas in my OB and because I'm on a lake where running out of gas is not that big of a problem. (knock on wood,hasn't happened yet)

Edited by - on

Russ.Johnson
Commodore

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USA
836 Posts

Response Posted - 08/06/2008 : 23:52:47

Stu,

Another factor might be 2-stroke vs. 4-stroke
I have a 2004 Honda-8 "Classic" 4-stroke.
I bought it new in July 2004 and had the 20-hour "Break-In" service in June 2005.
I noticed it started great the first month, then would take more and more pulls to start it each time.
I didn't think about it much and I didn't tell the dealer.

The dealer told me there was a build-up of varnish in the carb.
He was surprised after 20 hours there would be very much.

Here's my mistakes
1) I didn't drain the carb at the end of the season.
I didn't read the manual so that was my erro.
Luckily, it doesn't freeze here so it could have been worse.

2) The dealer recommended I disconnect the fuel line at the dock and let it run dry.
This will use the gas in the carb, so I don't have to worry about Step-1

3) I don't leave my gas tank on the boat.
So, I fill my 3-gallon tank each time I sail then at the end of the weekend, just pour the rest into my truck.
At most, my gas is 30-days old.

This might be overkill, but it's a simple process and I don't have any starting problems.

Russ

Edited by - on

OLarryR
Master Marine Consultant

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USA
3411 Posts

Response Posted - 08/07/2008 : 05:44:44

The practices each of us follow or don't have varied effects depending perhaps on how often we use the outboard and a bit of the luck of the draw. A long time ago, there was a thread that discussed some that had issues with the Honda and internals that can easily get clogged. This was on the 4-stroke. My thought is that in general, the 2 strokes were more forgiving with maintenance practices and lack of it. In my case, I am oftentimes sailing each week and when winter comes and I shift more to projects, I am still going out sailing each week unless temps really get down into the 30s. So, I do not have any layup periods and I do not run the gas out of the outboard each time as there is little chance of any gas deterioration but perhaps more of a chance of water/moisture issues if the gas line is run empty. Whether it needs it or not, by habit I add Startron to each tank fill-up and it is rare that my gas is older than about 1 -2 months. During the periods when I use the outboard less, I do windup filling the tank more often - more partial fills refreshing the tank with new gas. As far as octane goes....well my Honda Prelude uses premium gas and so rather than use the pump twice for regular and premium grades, I just out of laziness or efficiency (certainly not economically) just fill both gas tanks with the premium gas. I do same for when I bring my lawnmower portable gas tank to the gas station.

I have been performing all the maintenance myself and pretty much do almost everything while the outboard is on the boat except for the lower end oil change. On my 2006, I did that after a year when I had the boat out for a bottom painting, so i did not have to take the outboard off the boat even then. I will probably delay the lower end oil changeout this year with the rationale (whether it makes sense or not) that I use the motor frequently but for very short periods and so the total run time during the year is probably miniscule compared to if it was used on a motorboat. So, I plan delaying the lower end oil changeout this year...mainly so I can avoid taking the outboard off the boat. For the engine oil change, I use one of those manual suction pumps and suck it out of the dipstick. This is so easy and with no mess. The oil filter changeout is not too bad but I have to tape on a small drop cloth to capture any residual oil so I do not allow any to get into the river (not the most environmentally sound way to do this I admit but have been successful so far). Same goes for the gas in-line filter but that is an easier job with little mess.

I am wondering how many do the maintenance themselves and on-time according to the manual recommendations versus those that don't. Also those that either bring it in to a shop or have a guy take the outboard off and accomplish the maintenance. I guess whatever works for you as long as periodic care is performed should help reliability. Even if maintenance is skipped or someone uses old gas, it does not automatically spell disaster. Depending on how frequent you use the outboard and a bit of the luck of the draw - your specific outboard, has something to do with reliability.

Edited by - OLarryR on 08/07/2008 05:50:54

Happy D
Admiral

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921 Posts

Response Posted - 08/07/2008 : 05:56:29

<blockquote id="quote">quote:<hr height="1" noshade id="quote">The old fuel worked fine and the engine started on the fourth pull.<hr height="1" noshade id="quote"></blockquote id="quote">

Stu,
I think you answered your own question.
Dan

Edited by - on

cat1951
Admiral

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USA
636 Posts

Response Posted - 08/07/2008 : 08:21:16

I now have a lot of fuel (so to speak) for thought. I have two 5 gallon gas containers into which I add fuel stabilizer to keep it longer. I have a 2cycle Merc and since we don't go out that often, I am still on the first of the 5 gallon container after 2 years. The second still has 2 year old gas in it and it has never been opened. Although the engine is running fine, I think I am going to do 2 things. Reduce the size of the gas tank that is on the boat. That way I get more room in the fuel locker and I will be refilling more often. (We do expect to get out more now that some of our off boat projects are complete.) In addition to a smaller tank, I think I will move to only one 5 gallon fill tank so that the gas does not sit so long.

Now that I have that planned anyone want to buy some 2 year old gas? It's never been used.

Edited by - on

ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 08/07/2008 : 08:59:18

I've never run the gas out of the carb on my 1994 Honda 8. Starts the same as the day I bought it. However, I do run Techron-treated gas. IMHO: Techron = pretty good stuff.

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 08/07/2008 : 09:54:14

As to using old gas, at the end of the season, I use the remaining boat fuel in my snowblower. If there is any fuel remaining come Spring, I pour it into my truck and start the sailing season with fresh gas. In the last few years, I started using Stabil. Not because I was having any issues with stale gas, but just as a precautionary measure.

A year or so ago, I removed and dismantled the carburetor on my outboard, which was most likely the first time the carb was off since it was put on at the factory in 1995, and I was fully expecting to see some signs of varnish/gum/residue/sediment, especially in the bowl, but there wasn't a trace of anything. The carb was so clean on the inside it looked like it just came out of the box. With no traces of varnish after 12 years, I'm somewhat surprised Russ had varnish build up after 20 hours?

Like Bruce, I've never run the fuel dry out of the carb, and the outboard starts on the first half pull virtually everytime.

Edited by - on

aeckhart
Master Marine Consultant

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USA
1709 Posts

Response Posted - 08/07/2008 : 11:29:29

I use year old gas all the time in my 1989 Evinrude 9.9. I have been adding Sta-Bil in the fall to maintain some semblence of quality and have had to problems in 19 years.

The only maintenance I do is change or clean the plugs and change the lower unit lube every season before the boat goes in the water. I store the motor in my garage where the temps sometime drop into the teens in the winter. I've probably dodged a bullet here since I don't drain and refill the lower unit in the fall.

In any case, my Evinrude has never been hard starting or had a stalling problem due to bad gas............at least that I can recall.

Edited by - on

tinob
Master Marine Consultant

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USA
1883 Posts

Response Posted - 08/07/2008 : 12:01:13

I agree pretty much with what all have said, but must add that not all gas is alike. I also have a generator (4 stroke)in the barn that has stabilized gas in it whose age I can't remember, possibly three years or more old and this also starts on the first few pulls. The difference is that that gas never benifitted with oxygenation additives.
Originally we were dosed with MTBE which didn't harm the motors it was used with, just the drinking water from our aquifiers. We didn't run as well drinking that contaminated water as did our motors; minor problems with a variety of cancers,etc.

...Then the powers that be decided to switch the MTBE to ethenol as an oxigenating agent...well that worked well with our drinking water( so far) but not our motors. And the thing that laid my old 2-stroke Johnson low was when I topped of the previous years tank of MTBE fuel with fresh E-10 gas...this was not a marriage made in heaven

.
Read once a while ago that two stroke oil is a stabilizing agent, makes sense to me since I have never had a problem with two-stroke fuel regardless of its age.

NUFF SAID.

Val on Calista #3936, Patchogue, N.Y.

Edited by - on

Nautiduck
Master Marine Consultant

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USA
3704 Posts

Response Posted - 08/07/2008 : 15:16:58

In ten years of owning Honda "Classics" I have never drained the carb or run the OB with the fuel line disconnected to drain the engine. Never have had a problem. I do start each season with fresh fuel. Maybe this year I'll do the run it dry routine just to play it safe.

Edited by - on

piseas
Former Treasurer

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USA
2017 Posts

Response Posted - 08/07/2008 : 15:54:38

Personally, I like fresh fuel. Kinda of like day old donuts. Would you eat them? Would you eat 6mo to 1 year old donuts!!!
After long trips, I always have lots of extra gas. I empty that gas in my cars. Also not a good idea to keep gas laying around as my wife would remind me.
I have a 3 gallon tank on board and when it gets about 1/3 ro 1/4 empty, I go fill it up.
To me,not worth using or storing highly combustible fuel, anywhere, including your home. We have expensive motors, at least to me and service is not cheap. Why take unnecessary chances.
Steve A

Edited by - piseas on 08/07/2008 15:57:21

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 08/07/2008 : 19:20:49

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by aeckhart
 I have been adding Sta-Bil in the fall to maintain some semblence of quality and have had to problems in 19 years.<hr height="1" noshade id="quote"></blockquote id="quote">

Al,

If you are going to use Sta-bil, you should use it when you first pump your gas because the product just stops further degradation.

From the Sta-Bil FAQ's...

I have some gas in a tank that has been there more than 2 months. Will STA-BIL Fuel Stabilizer make this old gas like new?

No, STA-BIL Fuel Stabilizer will not restore or improve old gasoline. It will, however, stop it from degrading further. The best thing to do is treat the fuel as soon as you buy it.

Edited by - on

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