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The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.
I know many here use Seafoam in their gas so I thought I would pass along some interesting results in its ability to remove water/moisture from fuel vs K100. I follow this small engine repair mechanic out of Canada because he puts together informative, Well made videos and is professional so If your really bored of winter.... Seafoam https://www.youtube.com/watch?v=ATiPcX7TX-M&t=8s K100 https://www.youtube.com/watch?v=5p89dk5tZuE&t=0s
Scott-"IMPULSE"87'C25/SR/WK/Din.#5688 Sailing out of Glen Cove,L.I Sound
Ethanol based additive primarily just allow more water to be dissolved in the fuel before it separates, changing E-10 into E-11 or 12. Other surfactants do the same thing in some additives without increasing alcohol level. Except for storage over 60 days, proper fuel handling is at least as effective as any additive. Close the valve on your tank when not in use. I use two 3 gallon tanks instead of my old 6 so fuel doesn't sit so long and have gone back to running the engine dry after use. I also use a filter/water separator. Dissolved water doesn't get separated but harmlessly vaporizes during combustion. The filter would probably clog immediately if I had separation, but changing a filter beats cleaning a fuel system. Running dry probably doesn't have much effect but makes me feel better, which is probably what the additives do. Most additives are not harmful, so use your favorite, preferably non-alcohol, product if it makes you feel better.
Dave B. aboard Pearl 1982 TR/SK/Trad. #3399 Lake Erie/Florida Panhandle
Dave, The K100 isn't ethenol based. It treats ethanol fuels. Agree on fresh fuel is always best but that also relies on the source of the fuel being clean. Marina and gas station tanks are notorious for having water in them.and water effects small engine first due to the smaller jets etc. I always tell my wife to never buy gas at a station that is getting refueled from the truck. I really don't want the stirred up water and junk in the car.
Scott-"IMPULSE"87'C25/SR/WK/Din.#5688 Sailing out of Glen Cove,L.I Sound
K100 Stabilizer is butoxyethanol, two other listed major ingredients are alternative names for the same molecule. I guess that is to make it sound more complex. It's a butyl ether bound to ethanol and is a good, widely used solvent. It degrades and evaporates when exposed to air, but more slowly than ethanol and will keep the fuel water mix in solution longer. Phase separation occurs when water volume exceeds the capacity of the solvent, ethanol or butoxyethanl, to keep it in solution with the fuel, either by loss of the solvent or excess water. Water in solution is not a problem, nor is E-10 in an engine designed for it.
edit: A Mercury spokesman actually said E-10 is a good thing for modern marine engines in that it keeps the small amount of condensation water in solution and recommends it for their engines.
Dave B. aboard Pearl 1982 TR/SK/Trad. #3399 Lake Erie/Florida Panhandle
I've also been led to understand that ethanol's capacity to hold water in solution drops with the temperature, so cold nights and winter can cause phase separation. My large, built-in tank presents another set of dilemmas I won't go into here, but suffice to say I'm relying on a cocktail of StaBil Marine and Star Tron.
Dave Bristle Association "Port Captain" for Mystic/Stonington CT PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired), Now on Eastern 27 $+!nkp*+ Sarge
Stinkpotter is correct, everything except gases and vapors are more soluble at higher temperatures. Temperature cycling on a vented system is the primary source of water in fuel. I would also take a more aggressive approach in Dave's situation.
Dave B. aboard Pearl 1982 TR/SK/Trad. #3399 Lake Erie/Florida Panhandle
I switched from SeaFoam to Sta-Bil because it seems to handle the ethanol better. I still keep a bottle of SeaFoam on board for emergencies, in case I get some bad gas. Adding the entire can of SeaFoam to the tank will let me chug home.
As far as fuel storage goes, was SeaFoam updated for fuel with ethanol? Or is it chance that it helps?
STA-BIL is a petroleum based solvent, hyrolated light naphtha, that is also both polar and non-polar. It accomplishes the same thing as SeaFoam but is more stable, though either is adequate for our applications since most do not try to save fuel from one season to the next. It is what I use in my Miata and mower (4 gallon tank) for winter storage. I use it on the boat if I feel compelled to add something to the fuel because its what I have on hand. They all do what they claim, keep water dissolved in fuel, but claims for additional actions is generally voodoo. The real question is whether they are psychological placebo or necessary. Use your favorite brand if you choose since they do no harm.
Dave B. aboard Pearl 1982 TR/SK/Trad. #3399 Lake Erie/Florida Panhandle
I use either Stabil or Startron depending on what I select off my garage shelf. I will generally add it every time I fill up my portable gas tank. I have never had an issue with my 2006 Honda. However, I also have my boat in the water year-round and there is rearely a period of more than 2-3 weeks in the winter time that I have not started up the outboard.
There was a question I had a long time ago, if it is better to run the outboard dry when it will not be used for awhile. The thinking back when this was discussed was that if you do not use the outboard for say a month or so, then best to run the outboard so the fuel line goes dry. However, since I start up my outboard frequently throughout the year, it is then best to keep the fuel lines with gas as better insurance that moisture does not form/collect in the gas line.
In any case, I have never had an issue with starting my outboard...now over 10 years old.
Boy, tough question! I doubt that it matters as long as you run the engine long enough to flush the carb, close the tank vent afterwards and use up the gas within a month or two. What you do appears to have worked so far! Really, the amount of air entrained into the carb with expansion and contraction is so tiny that the question is meaningless in a practical sense. There isn't even consensus that running the engine dry is necessary; that might just be a carryover from the 2 stroke days and fuel/oil mixes. I don't do anything to my Miata except add Stabil and top off the tank for winter storage. I didn't even do anything in the old days when when my car had carbs and there was ETOH in the fuel. Its only vague opinion because I wouldn't know where to turn for actual evidence.
Dave B. aboard Pearl 1982 TR/SK/Trad. #3399 Lake Erie/Florida Panhandle
My experience with the same Honda 9.9 outboard as Larry was the opposite. That is because my use of the boat varies greatly - from twice a week sometimes to months between uses at other times. The wet gas in my tank would make starting hard.
I stopped storing gas for the boat, and after each use these days bring the gas tank home and pour the unused gas into my car's tank. I also always run the engine dry.
For winter I also open the Honda's carburetor bowl drain plug and catch the teaspoon of gas in a paper towel.
While running the engine dry I always connect a garden hose to the flush port with its brass adapter and flush the impeller and cooling system to remove salt water. By the time the engine stops with the fuel line disconnected, the fresh water flushing has run for two minutes or so and is complete. I was clueless when I bought the boat 12 years ago, and it took me 3 years to finally notice that I even had a flush port on my outboard! The owner's and the shop manual do not explain its use! It was thanks to the discussions here on the Forum that I learned about this possibility.
This simple but somewhat tedious method has allowed me to start the engine with one or two pulls every single time all spring summer and fall, including the first time each spring! It has electric start, but I now prefer to pull the starter cord instead. That gives me a feel for the compression of the 2 cylinders and the health of the system and does not depend on the level of charge of my battery.
I am so happy with the difference in performance of my 2002/2003 Honda 9.9 hp engine.
JohnP 1978 C25 SR/FK "Gypsy" Mill Creek off the Magothy River, Chesapeake Bay Port Captain, northern Chesapeake Bay
Hey John - It's been quite some time since we sailed together. Perhaps we can do another round of sailing on each other's boat this season ...May/June for starters !
Hey John - It's been quite some time since we sailed together. Perhaps we can do another round of sailing on each other's boat this season ...May/June for starters !
Hi Larry, Sure, I'd like that. I'll email you.
JohnP 1978 C25 SR/FK "Gypsy" Mill Creek off the Magothy River, Chesapeake Bay Port Captain, northern Chesapeake Bay
Notice: The advice given on this site is based upon individual or quoted experience, yours may differ. The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.