Managing Ethanol in Gas

[WIMUSKY]

Re: Managing Ethanol in Gas

I only run non ethanol premium. For one, as it sits the octane levels drop. How long does it take to drop significantly? No idea. I also use seafoam. This is what works for me. Never had an issue. Even if I'm wasting money on premium, so be it. I figure, if it aint broke, dont fix it....

 

[Randybeall]

Re: Managing Ethanol in Gas

After reading through the many replys almost everything has been covered except one. Yes, use a fuel stablizer, Startron is good, Seafoam is good, Sta-bil is good. By what you like. When it comes to storage time there are two choices, fill it completely or drain it. If you fill it completely and add a fuel stablizer it will be the same stuff in the spring as you put in in the fall. You must keep the air out, if you leave air space in the tank there will be expansion and contraction which will draw in moist outside air. Condensation will occure and you will have moisture in your tank. If you drain it you will need to pump it out into your water seperating filter come spring to make sure there is no water accumulation. As for using premium fuel, unless your engine manufacturer recommends it don't waste your money on primium fuel, two stroke engines do not need it. The compression is lower than a four stroke and the nature of the combustion is such that ping or detonaton is extremely unlikely. Remember, when you introduce that oil into the mix it lowers octane rating by a large number, deteroation of the fuel does not make that much difference. Burned pistons come from over advanced timing or lean mixtures, not low octane.

 

[jkust]

Re: Managing Ethanol in Gas

As I am in Minnesota as well and have boated 38.5 years including of course all of the forced ethanol years, I've never had an ethanol related issue in any of my equipment from snomobiles, outboards, I/O's, weedwhackers, snowblowers, cars, etc. When I winterize or summarize any equipment I simply add some Stabil. My 18footer's tank is 33 gallons but since I have young kids to tow and go fast a lot, I top it off generally after each use. Generally speaking, I keep it full as a matter of precaution with no consideration of ethanol during the season. I would suggest a water separator. If you are inclined, a handful of stations still sell non-ethanol gas which is also high octane. There are smartphone apps that list the stations...one is called Puregas.

 

[dingbat]

Re: Managing Ethanol in Gas

http://www.epa.gov/oms/regs/fuels/rfg/waterphs.pdf

Since the solubility of water in both gasoline and air decreases with a decrease in temperature, water can enter a fuel system through condensation when the atmospheric temperature changes. For example, assume a tank containing conventional gasoline contains only one gallon of fuel. Assume also that its closed while the outside temperature is 100 degrees F with relative humidity of 100 percent. If this tank is left sealed and the temperature drops to 40 degrees F, water will likely condense on the inside of the tank, and dissolve in the fuel. In order for enough water to condense from the air to cause gasoline-water phase separation, however, there must be approximately 200 gallons of air per gallon of fuel over this temperature drop (100 to 40 degrees). Since oxygenated fuels can hold even more water than conventional gasoline, it is even more unlikely that enough water will condense from the air to cause gasoline-water phase separation.

Another way water can enter gasoline is through absorption from the air. Water, in the form of water vapor, can dissolve in gasoline. The more humid the air, the faster the water vapor will dissolve in the gasoline. Due to chemical equilibrium, however, assuming a constant temperature, phase separation will never occur if the only source of water is from the air. Only enough water to saturate the fuel can enter the system, and no more. Water vapor, however, dissolves in gasoline very slowly, even at very high humidity. For example, at a constant temperature of 100 degrees F and relative humidity of 100%, it would take well over 200 days to saturate one gallon of gasoline in an open gasoline can (assuming the only source of water is water vapor from the air). Water absorption from the air is far slower at lower temperatures and humilities. (At temperature of 70 degrees and relative humidity of 70%, it would take over two years to saturate one gallon of conventional gasoline in the same gasoline can.) Again, oxygenated gasoline can hold more water than conventional gasoline, and would therefore take much longer to saturate with water.

Conclusion
Water phase separation in any gasoline is most likely to occur when liquid water comes in contact with the fuel. (Water in the form of moisture in the air will generally not cause phase separation.

 

[Captain Caveman]

Re: Managing Ethanol in Gas

I would suggest a water separator. If you are inclined, a handful of stations still sell non-ethanol gas which is also high octane. There are smartphone apps that list the stations...one is called Puregas.

A fuel-separator came standard on my 2009 Alumacraft Navigator. If one isn't coming with yours, then ask them to add it. You'd be surprised how much water builds up in the fuel. I was!

I'm like you though jcminnesota, I'm a 612er who heads up to the Iron Range each summer towing my boat. I get one to two trips in per month. I've got a 16 gallon tank with a 90hp Suzuki, and trust me, unless you are just barely moving at idle, you will be using up that gas. My engine manufacturer strongly recommends using the non-oxy gas, which I do. I know that I could save a few bucks but for the couple of tanks of gas that I use each season, the extra money isn't the issue. I know that I could leave that gas untreated in the tank for a few years without issue, so I don't worry about months. I do put in a stabilizer for the winter though!

Also, most resorts and marinas only have the high-octane non-oxy gas. It's always good to verify, but most do since there are a lot of motors that should only run that way and gas stations don't have the capability of running multiple gas types. There are some resorts/marinas that sell a special mix of 87-octane non-oxy gas as well. There are two places on Vermilion that do so for sure.

So either go non-oxy gas or treat the gas with a stabilizer. Either way I wouldn't worry too much about summer usage, since it's really more of the winter storage that you need to worry about treating the gas.

 

[jcminnesota]

Re: Managing Ethanol in Gas

Hay Thanks Capt! Its good to get a response from a local boating brother. I do know that at some resorts they use premium ethanol gas. I have read that mixing non ethanol with ethanol gas can be a problem. Do you have an opinion on that? I am trying to find out if MN allows MBTE in the non ethanol gas but am having a hard time finding out. Apparently that is the additive that can react and cause sludge to form in engines where the gas is mixed. I will follow your advice overall. My new boat comes with an onboard 10 micron filter and a second larger filter attached to the fuel line. However, there is no sight glass to see if its capturing water. Should I just plan to change the larger filter a few times a year? Once a year? What do you recommend given that our use pattern seems to be about the same. Thanks Again....

 

[Captain Caveman]

Re: Managing Ethanol in Gas

At least with my Suzuki motor, while they recommend the non-oxy gas they said it doesn't hurt to use the regular but not to do it often or to leave it in there. I've mixed gas in both my truck and my lawnmower without having a problem, but I don't do it much. I mostly run non-oxy in all of my recreational motors - chainsaws, snowmobile, old boat motors ('57 & '63), and new boat motor. I know that the gas debates have raged on in many internet forums and bars, but I certainly noticed a difference myself. I went from having to rebuild my triple carburetors every year on my 1997 Polaris snowmobile, to not doing it once since I switched to non-oxy gas. It's been over 5 years since I last touched those things and it's running like a champ this season.

The filter on my boat doesn't have sight glass either. It's just looks like a black oil filter from a car/truck. I just empty it once a year when I do all of my year-end maintenance in the late fall. I'd check it more often if I were boating every week.

 

[ondarvr]

Re: Managing Ethanol in Gas

The possible problem with blending the fuel has nothing to do with them being compatible or causing problems on their own, they will work fine by themselves or blended.

The possible problem comes from using E-0 95% of the time and then using E-10 on occasion. E-0 will not blend with water, so all water that enters the system will remain in the bottom of the tank until it builds up to where the pickup tube sucks it into the motor. At this point the motor either dies or runs poorly. E-10 on its own will absorb water, so less water will be in the tank unless a large amount is introduced at one time, then it may overwhelm the ethanol and settle to the bottom of the tank. This water and ethanol blend will have little or no oil in it but still may allow the motor to run, this is when damage may be done.


A water separating filter will do nothing to protect the motor from water being ingested because if the water is blended with ethanol it will pass right through, only water that is free floating will be blocked from getting to the motor.

MN does not allow MTBE in gas. I check my screw on filter every year, in the 12 years of using this boat I have never found any water in the filter, been using E-10 for 20+ years.

There is much more to type, but it gets old repeating it every week.

 

[Timeking]

Re: Managing Ethanol in Gas

OK, you guys, couple issues with above posts. I am a chemist.
(1) Water sinks. Since it is on the bottom of the tank, and the pickup (I assume) is also on the bottom of the tank, then if water is present, it is the first thing sucked up into the engine. Not the last.
(2) Water vapor gets into the tank from the air. The more air in the tank, as the temperature goes up and down night and day, more water vapor enters the tank and gets dissolved into the ethanol. Why would you want to store your tank half full when that means you have half a tank of air breathing in and out? Why not fill it after every use, and keep it filled?

A question I -DO- have is that if I burned 30 gallons of gas out of my 67 gallon tank and there was only a BB size droplet of water in my fuel-water separator, then the fact that my engine suddenly quit running properly (stalled, idles like crap) is NOT due to ethanol separation but probably due to some other (likely expensive) problem. How do you know for sure that the gas is OK? Throw a match down the fill tube?