SippyRat

looking for opinions on how to prepare my fuel for the first run of the year.

i have a 2005 525 efi. the previous owner used stabilizer in the 87 octane fuel last fall. i have about 20 gallons in the 75 gallon (aluminum) tank. i have been told by merc racing and other 525efi owners that the motors run best with 87 octane and there is no benefit to running higher octanes. however i have been thinking of running ethanol free because of all of the problems related to ethanol. i have easy close access to ethanol free 91 octane. would it be alright to top off my tank with this or should i just use 87 and run it down low before switching to ethanol free?

probably several questions in one here but any advice would be great

FIXX

iTrader: (2)

fill it with 91 and go easy for the first tank of fuel..thats if its lasy years fuel..

Wes Burmark

Wonder why previous owner left tank 1/4 full for the winter? Far better to leave the tank almost full for storage (for the future). Did the previous owner use "just a fuel stabilizer" or a product designed for storage of E10 fuel? If it were my boat I would get as much of the old gas out and use it in my mower! If you can get ethanol free gas for your boat that would be nice. You will be paying for octane that you don't need but it's only $$$$! LOL

stevesxm

20 gals at 4 $ / gallon... hmmmm thats.... 80 $

how much are pistons if you are wrong ? hmmm let me think ....

look in the dictionary under " self inflicted disasters while trying to save a few bucks "... your picture could easily be there soon.

pump it and put it in your lawn mower or just dump it... then run a bit of clean fresh fuel thru everything and just start fresh...

please...

articfriends

iTrader: (1)

I completely agree, some people forget that the base stock used in 10% ethanol 87 octane gas is between 82-84 octane which means when the gas phase seperates from the Alcohol ( when your boat sits with a vented to atmsophere gas tank) you are left with a witches brew of super low octane garbage gas and even worse brew of ethanol and water that although has alot of octane , it will lean your motor right out if you suck it up, I would pump it out and run it in mower or beater car. A 525 is a 25,000$ plus motor, why chance it, Smitty

pstorti

iTrader: (2)

+1

fireguy

I thought I read a service bulletin from Mercury advising that the long standing belief of sroing your tanks as full as possible for the winter, was no longer desired.

From what I understand if the fuel does go bad then you just have more junk fuel to pump out and dispose of. That was my understanding.

Somebody smart please correct me asap if this is wrong, cuz I don't want to be that guy.

Redhook98

I have run 2-year old gas before (E-10). I loaded it up with Seafoam, Octane boost and HEET. Over $100 in additive into 2 gallons of gas (to mix it for the tanks) Lol! It saved 250 gallons of gas several years ago when it was $5+ per gallon at the marinas.

But this was with a pair of 1963 327 Corvette Chris Craft motors in a '63 Roamer. Probably a little more forgiving.......

I would fill up with high-octane, add a little Seafoam and Startron, retard the timing a few degrees and run like ya stole it. (kidding) Your diluting the gas enough and compensating for the potential lack of octane due to separation. 1 year old gas that has been treated really is not a big concern. I run a lot of different boats in this exact situation. Just make sure you add good fuel to it first.

mike tkach

iTrader: (3)

+2,i have done it many times with no problems.

Captain YARRR

If we were talking a YEAR AGO sure, but we are only talking about last season. Probably 3/4 of us are doing the same thing.

Add some treatment like suggested and go for it. I think suggesting you are going to burn up a piston is a bit too much.