Octane vs ethanol (again, I know )

[thegotoguyr]

I've been trying to research an answer to my question, there does not seem to be a clear answer.
I have access to ethanol free fuel but it has a 92 or 94 octane rating and is more expensive by about $30 a fill.
If I fill with 87octane with 10% ethanol plus a $15 bottle of additive the difference in dollars is not an issue if I am burning a cleaner fuel.
I understand the ethanol, phase separation water issues and I also understand higher octane for timing advance and knocking issues should not be a concern on a mpi engine with electronic timing sensors.
So my question is: Is there any disadvantage or possible engine damage by burning the higher octane with no ethanol?
To me if its a better fuel for a few bucks more it's a no brainer.
Thanks for any thoughts.

 

[sporters78]

Better fuel and no problems, even with the additive ethanol fuel is crap

 

[edthearcher]

this is my 2 cents, to answer your question if you are going to use ethanol fuel as in a car or a boat and want to say money, i say go head , if your going to let it set in your boat gas tank idle for over 30 days, your asking for trouble, if you park your boat for the winter, with ethanol fuel in it you are asking for trouble, i destroyed a brand new chain saw because i let it set with ethanol gas in it. i own 2 cadillac,s and a dodge truck, 2 riding lawn mowers,plus more. non of my vehicles ever use ethanol unless i,am traveling and cant find non ethanol. i have proven over and over i get better gas mileage with non ethanol, i have a friend who owns a small marina, he told me his repair business has encreased 4 times since the start on ethanol

 

[MonacoMike]

this is my 2 cents, to answer your question if you are going to use ethanol fuel as in a car or a boat and want to say money, i say go head

While I agree with most of your post point this would only apply to a fuel system that has ALL alcohol resistant parts. Alcohol eats rubber whether you use it fast or slow.

MM

 

[thegotoguyr]

Thanks for the replies. I think we all agree that ethanol sucks, my concern is with running a higher octane. They say the engines are designed to run with a minimum 87 octane so when is there too much octane?

 

[Dieseljeff]

I don't believe you could possibly damage an engine because of a higher octane fuel...if anything, it may be a waste of money if you can't adjust the timing to take advantage of it. Personally, I try to only run the non-ethanol in my boat, generator and outboard. I ran a honda genny for several years with stabil and have still had to take the carb apart 2 or 3 times to clean the goo from the ethanol.

Jeff

 

[MonacoMike]

Thanks for the replies. I think we all agree that ethanol sucks, my concern is with running a higher octane. They say the engines are designed to run with a minimum 87 octane so when is there too much octane?

Below was a discussion I had with a member a couple of years ago on a similar subject.

MM...

The link was simply to show the recommended octane to help demonstrate what I meant when I said Mercruiser recommends 87 octane. It is NOT for a 2013 repower, Mercruiser neither produces nor repowers with 8.1's any more and hasn't for almost 3 years. The 8.1 was replaced by the 8.2...which has the same recommended octane rating of 87. That said, the Merc manual as far back as 2003 recommends 87 octane.

No it does not as I read it. Mercruiser does not use the word "recommends" in any form. It is as I stated earlier:

"Mercury MerCruiser engines will operate satisfactorily when using a major brand of

unleaded gasoline meeting the following specifications: USA and Canada ‑ having a posted pump Octane Rating of 87 (R+M)/2 minimum. Premium gasoline [92 (R+M)/2 Octane] is also acceptable. Do not use leaded gasoline.​

"​

Mercruiser does not seem worried about running higher octane fuel in the manual, note no disclaimer.

Mercruiser further warns against ethanol gasolines and describes the damage that can occour:

" If the gasoline in your area contains either methanol (methyl alcohol) or ethanol (ethylalcohol), you should be aware of certain adverse effects that can occur. These adverseeffects are more severe with methanol. Increasing the percentage of alcohol in the fuel can also worsen these adverse effects.Some of these adverse effects are caused because the alcohol in the gasoline can absorbmoisture from the air, resulting in a separation of the water/alcohol from the gasoline in the fuel tank.The fuel system components on your Mercury MerCruiser engine will withstand up to 10% alcohol content in the gasoline. We do not know what percentage your boat's fuel system will withstand.
Contact your boat manufacturer for specific recommendations on the boat's fuel system components (fuel tanks, fuel lines, and fittings). Be aware that gasolines containing alcohol may cause increased:
• Corrosion of metal parts
• Deterioration of rubber or plastic parts
• Fuel permeation through rubber fuel lines
• Starting and operating difficulties"

To be certain they did not say you couldn't use ethanol fuels, they just disclaimed responsibility.

As for paying the price for octane that is not needed, you could always get by on the "minimum" but that is not how I roll. It makes no difference to me what gas you use but others reading this thread need to know the facts about gas, the risks, and the costs associated with various mixtures of gasoline.

Hope this helps you in your decision.


MM​

 

[AMFM3]

All great info. But here's a scenario that nobody has thought of.

Enclosed lake, slipped boat that is not trailerable. The only fuel on the lake has ethanol. What do you do? Moving lakes isn't possible for whatever reason. What then? Sell the boat? Get out of boating? Find a new job?

im not in this situation. My marina doesn't sell ethanol and on,y sells 89 and 92. I'm just wondering given the vitriol here about ethanol.

Mark

 

[Lazy Daze]

No issues with running higher octane. Just a waste of money.

Both personally, and with all of the boats that come into the shop, we have NEVER seen issues when 87 octane with the proper additive has been used. Run e-free or use the proper additive - both will result in a long, long engine life. If you run the e-free, still make sure to use a stabilizer if the gas isn't being used up quick enough, though. It's not "entirely" necessary, but it's an awful good idea.

FYI, the additives that you would need to add for a 40-gallon fillup of 87 octane will add under $2 to your total bill. Although, granted, most of us don't measure exactly and tend to go overboard on the additives, so maybe $3. But then, we're also getting the stabilizer, too.

 

[MonacoMike]

All great info. But here's a scenario that nobody has thought of.

Enclosed lake, slipped boat that is not trailerable. The only fuel on the lake has ethanol. What do you do? Moving lakes isn't possible for whatever reason. What then? Sell the boat? Get out of boating? Find a new job?

im not in this situation. My marina doesn't sell ethanol and on,y sells 89 and 92. I'm just wondering given the vitriol here about ethanol.

Mark

Mark, many folks deal with this issue constantly.

If one must use ethanol I would:

Change all fuel hoses to alcohol resistant.

(Few vessels, older than 10 years or so, have alcohol rated hoses.)

Install twin high quality fuel filters.

(Alcohol in ethanol is a great cleaner, and that sounds good, until you realize it is cleaning years of gunk and running it to your fuel system)

Install a water separator if not present.

(Hopefully it will keep separated water from the tank at bay.)

Run a quality stabilizer like Startron.

Become proficient at rebuilding carbs.

(No marine techs I have talked to believe Mercruiser or aftermarket carb kit manufacturers are now building their kits to alcohol fuel standards.) (Hope someone knows otherwise and has documentation of it.)

As for the strong feelings concerning this issue, it was brought about by a coalition of the farmers lobby and the environment lobby. The environment lobby have since found that their dreams of ethanol renewable fuels have lead to consequences they never intended and most no longer support ethanol fuel. However the farmers lobby is so deep in the politicians pockets they will likely never get this folly overturned.

MM

 

[MonacoMike]

Both personally, and with all of the boats that come into the shop, we have NEVER seen issues when 87 octane with the proper additive has been used. Run e-free or use the proper additive - both will result in a long, long engine life. If you run the e-free, still make sure to use a stabilizer if the gas isn't being used up quick enough, though. It's not "entirely" necessary, but it's an awful good idea.

Dennis,

This is totaly different than the local marine shop techs in my area tell me. They tell me they have seen an enormous increase in fuel system issues since ethanol became common. Particularly the carbed engines have the most problems and some have never ran right since the owner used ethanol fuel. Outboards too have issues. Ethanol is a particularly difficult issue for Midwest boaters as most trailer a time or two a month over three or four months and then the seasons gone. Very few folks at my marina buy fuel more than a few times a season. (Hopefully lower fuel prices will help this season.)


All this leads to constant fuel system issues on vessels not built for any alcohol in the fuel.

MM

 

[Lazy Daze]

Mike, without using a proper ethanol-fighting additive... yes, plenty of problems. But so far, for those that use the proper additive religiously, all has been good. Of those that have problems, it also has been more prevalent in small outboards. Don't get me wrong, though, I am in NO WAY a proponent of ethanol. Less BTU's per gallon, increased chances of problems and more expensive. Nothing good. Bring back MTBE.

 

[ZZ13]

I have a carbed 3.0L Mercruiser in my 2009 175 Sport. Its been six years of exclusively E-10 from the auto gas pump with me adding Startron each time. For a while the boat was 550miles from my home and sometimes that fuel sat in there for 6-8 months. Started right up even after those long periods and gives me no problems. Everything on the boat is still original (even the battery), except the impeller.

 

[MonacoMike]

I have a carbed 3.0L Mercruiser in my 2009 175 Sport. Its been six years of exclusively E-10 from the auto gas pump with me adding Startron each time. For a while the boat was 550miles from my home and sometimes that fuel sat in there for 6-8 months. Started right up even after those long periods and gives me no problems. Everything on the boat is still original (even the battery), except the impeller.

Bill, I would expect and hope your experience with ethanol would be acceptable. If not I'd be dissapointed in Sea Ray. The law, mandating ethanol blending was passed in 2007 and most manufacturers were building to ethanol specs after that. By 2011 everything should have been capable of running ethanol without issue. The problem in the marine segment is the huge number of pre-2007 vessels, that are still great boats, that are not prepared for ethanol consumption still in use.

MM

 

[northern]

I do not know about your area but where we have a farm the only bulk fuel we can get that is 100% oil is high octane. Call the bulk dealer in your area he should be able to tell you what you can get and from what retailer.
I do not think you can buy 78 non methanol gas any more.
Any one in the gas business can help us?

 

[thegotoguyr]

Thank you all,for helping me out while I was out on the lake. It has helped me decide that is is worth the extra few bucks to run the e free gas. I fill up maybe 5 or 6 times a year in our 6-7 months of boating season and a higher octane won't hurt. My boat is pre 2007 so I think its worth not worrying about what MIGHT be happening inside my engine.
Mark, I checked in on a slow putt past AMFM III , she looks good, just a little itchy to get out.
I understand saving a buck a gallon on those large fuel tanks some of you have, that would add up bigtime, but for me, an extra few hundred a year for a better gas is not an issue

 

[ttmott]

The stoichiometric ratio for the ethanol to be burned is quite a bit greater than gasoline (9.1 vs 14.7). This means that for the same amount of work produced there is required more fuel. As a result gasoline mixed with ethanol is less efficient than pure gasoline and the greater the ethanol percentage the more is needed for the same mileage. An automobile running E85 gets just more than two thirds the mileage as running on gasoline. With all of that said ethanol in it's pure form has an octane rating of 112 so gasoline mixed with ethanol has a bit of a greater knock resistance. In the end from a total work output there is no real advantage to mixing ethanol with gasoline other than the entertainment of politics.
The challenges with carbureted engines is the ethanol component in gasoline tends to create high viscous materials primarily due to water and thus tends to restrict the small ports and orifices in the carburetors; Most apparent in small engines with comparatively small carburetors. Ethanol in up to 10 percent has shown little negative effects with respect to corrosion in engines produces after 2008 and for those pre 2008 a change in hose material and a water absorbent is all that is needed.

As an edit ethanol has a greater latent heat of vaporization which means it is harder to ignite and thus in cold environments will create a hard start condition for earlier engines especially carbureted...

 

[AMFM3]

Thank you all,for helping me out while I was out on the lake. It has helped me decide that is is worth the extra few bucks to run the e free gas. I fill up maybe 5 or 6 times a year in our 6-7 months of boating season and a higher octane won't hurt. My boat is pre 2007 so I think its worth not worrying about what MIGHT be happening inside my engine.
Mark, I checked in on a slow putt past AMFM III , she looks good, just a little itchy to get out.
I understand saving a buck a gallon on those large fuel tanks some of you have, that would add up bigtime, but for me, an extra few hundred a year for a better gas is not an issue

Thanks! AMFMIII is still on blocks! Apparently the lift at the Marina is awaiting parts. If you cruised by on water, then that's Four Playin' beside my spot. She's for sale and been in the water all winter! I'm waiting for bottom paint...two weeks late.

See you out there soon!

Mark

 

[Lazy Daze]

According to Merc, there's really nothing "more" to be worried about in regards to ethanol (10%) when comparing a new engine to one that is, say, a 1990 model. The parts that were used in terms of metal and rubber are the same. However, there is another side to this that sometimes gets overlooked -- Ethanol is a very good "cleaner", which means varnish/sludge/gunk/whatever that has built up in the fuel tank or the lines will now start to be loosened up and sent towards your engine, which is of course, not a good thing. However, the use of a good fuel/water separator (filter) will take care of catching any nasty particles. It's a good idea to keep an extra filter on board at all times, in case it gets clogged up. 4-cylinders didn't come, standard, with a stand-alone filter - but can be easily added for extra piece of mind.

 

[paulswagelock]

I talked to Merc specifically when contemplating adding an external fuel / water separator to my system (with cool fuel module) and was told you can't add in the extra filter due to pressure drop. Keep that in mind if your boat is newer.