I've often wondered how long the "ethanol free" stuff sits in the tank waiting to be bought. I believe it's best to buy gas from a location that sells a bunch. That way the "new" gas is fresh.
I've often wondered how long the "ethanol free" stuff sits in the tank waiting to be bought. I believe it's best to buy gas from a location that sells a bunch. That way the "new" gas is fresh.
And you would believe correctly…..as clearly stated in the FAQ on fuel….Originally Posted by Woody b
Fuel Selection:
Make your fuel selections based on the following criteria, IN THE FOLLOWING ORDER:
-High Traffic, Top-Tier (Name Brand) Fuel
-Appropriate Octane Rating (see above info)
-Lowest possible ethanol content (NEVER to exceed 10%).
-While it may be preferable to utilize a fuel that contains lower (or no) ethanol, use of fuels that are SUBSTANTIALLY higher octane can result in decreased performance, decreased fuel economy, and potential for carbon buildup. Higher octane fuels burn SLOWER and COOLER.
Last edited by JS!; 05-28-2023 at 12:21 PM.
2015 Tracker Targa V18 150 4-Stroke 2B142247 9.9 EFI Pro Kicker 1R159535
2001 MasterCraft Maristar 210 V-Drive, LTR 330 HP
The other thing is how long a tank of fuel sits in your boat. 87 octane loses octane much faster than higher octane fuels. In 3 months, 87 octane fuel starts to break down. Whereas it takes about 9 months for the higher octane fuels. Keep in mind 87 octane is the MINIMUM octane rating for fuel in your motor, so if it sits for 3-9 months, it could be much less octane and you'll see degraded performance and could have other fuel related issues. A boats gas tank with a fuel vent open to the atmosphere is not ideal storage.
"87 octane fuels tend to be less refined and contain more unstable hydrocarbons. As the months pass during storage these unstable components react to form gums, varnishes and lower octane hydrocarbons. As a result the octane can decrease within months for 87 octane fuels, especially when stored under less than ideal conditions. 93 octane fuels are more refined and contain more stable hydrocarbons. These stable hydrocarbons can last 2-3 times longer than 87 octane fuel. Even in proper storage 87 octane gas can start to degrade in 3 months, 93 octane fuel should last closer to 9 months before degradation is noticeable. Keep in mind that 93 octane fuels are still susceptible to octane loss and vapor pressure decreases due to butane evaporation."
Octane Stability: High Octane vs Low Octane Fuels (sunocoracefuels.com)
^^^^^^
No self respecting boat owner I know of would let a tank of gas sit 3 months, especially down here. But I guess if you are snowed in, but don't they treat and empty their tanks for winter?
There are some true statements there regarding refining and hydrocarbons. But the theory that higher octane fuels don't lose octane or degrade within 3 months is utterly false.
Todays fuels begin to degrade 15 days after they are pumped. You'd be amazed what we see form in small fuel system passages/orifices after only 60 days, even with High-Octane fuel. DON'T rely on this theory as it's going to catch your wallet coming AND going.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
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I always purchase fuel from a high traffic Top Tier rated gas station (usually an Exxon near me). I usually run 87 octane non ethanol. The last time I filled my portable jugs, I noticed a disclaimer in fine print on the non ethanol pump that said this was ("not an Exxon branded fuel"). That probably means it is likely that it does not have the top tier additive package like the ethanol containing Exxon fuels on all the other pumps. So even purchasing non ethanol fuel, sold at Top Tier branded gas stations, is not a 100% guarantee you are buying top tier non ethanol fuel.
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That is straight from Sunoco's website. Their engineers know a lot more than I do about fuel degradation and loss of octane. I will say boat fuel tanks are not ideal places to store fuel with a vent always open to the atmosphere. Plus you're always mixing new fuel with old fuel when you fill up, unless you ran out completely. A steel fuel can or drum completely sealed to with fuel almost the very top would be a lot more ideal. I always use 90 octane and ethanol free.
I managed/maintained a 2006 27' whaler from new until 2 years ago for very wealthy owners, 2-225hp i6 verado's. The owners used the boat 2x a year, I ran it monthly for 2 hours (1 hour on plane at 4,000 rpms +). It held 200 gallons. In the first 5 years I'd keep it full and literally only add fuel once a year when it got down to 80-120 gallons. After that, I would fuel it every 6 months and put 50 gallons in to keep it between 80-130 gallons in case they used it, it would cover anything they wanted to do.....in 2021 it had 550 hours on it. We never once had a fuel related issue with anything. Not even dirty fuel filters and the boat sat on a lift directly in the South Florida sun, year round.........After that, I swear by the stuff.
Last edited by Capt James; 05-28-2023 at 11:04 PM.
Has anyone checked gas lately to see what the ethanol content "really" is? When I worked at a Chevrolet dealer we has a meter to easily check it using a DVOM. I rarely say more than 2% to 3%. I've been gone from there for 7 years. I'll check the alcohol content in my boat tank later using the old fashioned method.
5-7% seems to be the average in most metropolitan areas.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
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