Use of 90 octane gas

Remembrance

I have a Mercruiser 6.2l and have always used regular gas. My marina only offers 90 octane gas. Will I have any issues if I use the 90 octane?

Black_Diamond

Probably (if lucky) it is Rec Fuel (no ethanol). Will run just fine. 

Ian

Yes, the key is ethanol or not and how much you burn off. If it has ethanol and not being used there is the risk of separation. Plus legality to use. See this article https://www.boatus.com/news-room/release/boaters-beware-expect-more-e15-this-summer

Michael T

I would recommend absolutely no ethanol for your engine and that is imo unlikely unless it is 90 or higher.

mattie

Absolutely fine to run 90 octane. As above - the key is no ethanol.

Octane is the opposite of what people think. The higher octane number represents a less volatile & better controlled burn. Higher compression motors need the higher octane because as compression goes up - so does the chance of pre-detonation, spark knock, run-on. All bad things for modern motors.

87 is actually more volatile & less predictable. Minimum standard for most motors with normal compression.

If your motor is labelled to run on 87 - running 90 won’t hurt it at all, although no benefit either.

Again - no ethanol blends should be run in marine engines.

LaRea

mattie said:

... no ethanol blends should be run in marine engines.

A different view:  IF YOU HAVE A CHOICE, don't buy ethanol fuel.  Otherwise, run the E10 and don't give it a second thought.  It will not hurt your 2008 boat.  

I say this from direct experience.  Non-ethanol fuel is not sold at any marina within 100 miles of me.  I've been running only E10 for 20+ years (three boats, total 1500 hours).  I've never had an issue with E10 fuel, and never known anyone who had problems with it. 

Don't leave E10 sitting in a tank for 1-2 years, but in normal use it's fine.  

PickleRick

My 20 plus year old boat doesn't mind ethanol up to 10%. Im sure my carb and fuel pump gaskets don't like it.  

I put in stabilizer each time i fill up.  Id do the same with non ethanol.  My boat is paid for by those who dont use fuel stabilizer

69fastback

LaRea said:

mattie said:

... no ethanol blends should be run in marine engines.

A different view:  IF YOU HAVE A CHOICE, don't buy ethanol fuel.  Otherwise, run the E10 and don't give it a second thought.  It will not hurt your 2008 boat.  

I say this from direct experience.  Non-ethanol fuel is not sold at any marina within 100 miles of me.  I've been running only E10 for 20+ years (three boats, total 1500 hours).  I've never had an issue with E10 fuel, and never known anyone who had problems with it. 

Don't leave E10 sitting in a tank for 1-2 years, but in normal use it's fine.  

Same for me. I run it in everything and have been for a lot of years, because that’s all we have. My Rinker, bass boat with a 2 stroke outboard, lawn equipment, 2 stroke dirt bikes, 4 stroke dirt bikes and quads, 9 second carbureted street car.  I left my car sitting for 3 years with e10 in the tank, while doing some upgrades, and had no problems at all when I started it back up. 

Willhound

Same here. I dump a couple bottles of Startron in the tank every couple of fill ups. No issues in 4 seasons.

Michael T

Not a fan of E10 for anything. Damages are not always apparent and can build over time. I am really surprised that some of you "have no non ethanol for 100 miles"  For the 300 miles of the St. Lawrence that I boat on you can only get 91 or higher non-ethanol and diesel. Dumping Startron and its cousins into each fill-up is pretty expensive. My 2014 502 Mercruiser Magnums specified 91 or higher octane. My 2020 Yamaha Supercharged SVHO strongly recommends 91 or higher ethanol free gasoline. Even 10% ethanol can cause fuel system erosion and a myriad of other time accruing problems. ALL ethanol results in power loss. A few years ago we had this discussion and performance charts were published showing the power loss at various rpm bands across several different engines. In many cases it was up to 20% power loss and distance loss. IMO if you have the choice use non-ethanol. 

LaRea

Don't get me wrong - I'd love to get E0 fuel, and I'd gladly pay extra for it.  On most of the Chesapeake Bay and tributaries, it's not an option.  I've never seen it at any marina on the Potomac, and that's everything within 100 miles of me.  

A lot of people say that running E10 in a boat can have catastrophic consequences.  Maybe that has been true in isolated cases.  There's no widespread evidence of it here in the land of 89 octane E10.  

mattie

We have a great marine gas bar called Desmond's in Port Huron Mich. (can't cross into U.S. r/n thx CV-19!)

The cute gas jockey girls always ask, you want the cheap gas? Or the good stuff?

69fastback

There isn’t any non ethanol gas here. My next performance car build is going to be a turbo motor and I’m excited to use e85 because it has a lot more power capabilities than standard pump gas. E85 is sweet nectar from the horsepower gods. It’s made 4 digit horsepower street cars very easy to achieve. 

Dream_Inn

MT, you are very lucky with your non ethanol fuel.  I only know of 1 place on the Chesapeake that sells it, in Cape Charles. Only takes me 200 plus gallons of fuel to get there. 

212rowboat

if the motor is modern it'll run ethanol just fine.  it just won't run at peak like it will with non-ethanol unless you tune for it.  ethanol is actually higher in rand count than gasoline- meaning it's more stable. when it's mixed with gas it loses that stability.  there is also a lot more power by volume in gasoline than alcohol, but alcohol burns faster... hence, it's good for power but hotter and won't go as far.  

i had a set of ski-do's in the four stroke variety, closed cooling rated at 265hp (boosted).  i ran rec fuel in the 91 to 93, sometimes 94 octane rating and those skiis would break 70mph and tickle 75mph in the right environmental conditions.. same everything except running 93oct e10 and i could barely break 60mph... there was that much difference... i'd also blow through a tank of fuel in about 2/3rds the time running e10 than rec fuel.  

blue fuel is still a thing around here... it's literally blue- dyed...  it's E0 105~110octane racing fuel.  it's out of my way to get and there is no benefit to running it in any engine i now own, BUT... you could take, in theory, a boosted engine with 11:1 mechanical ratio or somewhere around 9:1 dynamic ratio and feed it that stuff, and advance spark way up there around 37*~38*, and see some major benefit.... it's kinda funny, though, because you can NOW do the same (as @69fastback offered) with E85 and a tune designed for it... just don't expect it to take you as far as gasoline will... no matter what a tune does, it can't add to the stored energy by volume of gasoline... sorta like gasoline can't compete with the stored energy by volume of diesel... 

the problem with ethanol in a boat is a: corrosion.  and with a modern engine that has fuel system parts to account for that corrosion it's b: it attracts water.  

davidbrooks

@Dream_Inn my marina on the Severn Sells 89 octane fuel.  No Ethanol. http://www.smithsmarina.com/amenities.html Fuel dock is about 20 ft away for me.

LaRea

Beotch.

LaRea

Also thanks to my favorite Canadian, @Michael T , for sharing that he enjoys 91 E0 along the entire St. Lawrence.  Now you're just showing off.      

Willhound

The corn/ethanol lobby isn't as strong in. Canada. More ethanol free fuel. In some areas.

69fastback

212rowboat said:

if the motor is modern it'll run ethanol just fine.  it just won't run at peak like it will with non-ethanol unless you tune for it.  ethanol is actually higher in rand count than gasoline- meaning it's more stable. when it's mixed with gas it loses that stability.  there is also a lot more power by volume in gasoline than alcohol, but alcohol burns faster... hence, it's good for power but hotter and won't go as far.  

i had a set of ski-do's in the four stroke variety, closed cooling rated at 265hp (boosted).  i ran rec fuel in the 91 to 93, sometimes 94 octane rating and those skiis would break 70mph and tickle 75mph in the right environmental conditions.. same everything except running 93oct e10 and i could barely break 60mph... there was that much difference... i'd also blow through a tank of fuel in about 2/3rds the time running e10 than rec fuel.  

blue fuel is still a thing around here... it's literally blue- dyed...  it's E0 105~110octane racing fuel.  it's out of my way to get and there is no benefit to running it in any engine i now own, BUT... you could take, in theory, a boosted engine with 11:1 mechanical ratio or somewhere around 9:1 dynamic ratio and feed it that stuff, and advance spark way up there around 37*~38*, and see some major benefit.... it's kinda funny, though, because you can NOW do the same (as @69fastback offered) with E85 and a tune designed for it... just don't expect it to take you as far as gasoline will... no matter what a tune does, it can't add to the stored energy by volume of gasoline... sorta like gasoline can't compete with the stored energy by volume of diesel... 

the problem with ethanol in a boat is a: corrosion.  and with a modern engine that has fuel system parts to account for that corrosion it's b: it attracts water.  

This all very correct. If I had pure gas here, I’d run it, but I don’t worry about e10 in my stuff. Even with tuning, a normal aspirated engine won’t see a lot of benefit from running e85, but when you add boost, it does amazing things. We tried running e85 in our nitrous car and it didn’t work as well as a boosted motor because of the moister it creates even when you’re burning it. We saw some gains over regular pump gas, but the tuning window was very small and not worth the gains like in a boosted application. 

212rowboat

i'm not a fan of ethanol unless it's bottled... but in fairness much of it's evil's (aside from cutting into economy which hasn't been fixed; can't be fixed) was early on when people were running engines not designed for it. 

a soft gas line back then was a piece of black hose, as an example... now, it's still black on the outside, but has layers on the interior- one of which is impervious to decay/oxidation and breaking up.... sending parts of it throughout the fuel system, engine, and into the catalytic converter.... 

i built a mopar 360/408 for a tow motor (RV 'sausage' cam) from the ground up once... i pulled the injectors and the baskets had a film that was visibly dark on them... after replacing the keg intake manifold with an edlebrock air-gap, and moving the fuel lines as a result (specifically the rail's cross over) that problem went away for the most part.  After pulling it to get to a collapsed lifter not long after and inspecting the rail- there was now a whitish 'oxidized' look to the interior of the rail (seen from the ends anyway), and that was the ethanol eating up a metal that wasn't designed for it... swapping rails to a billet steel and whatever magic of metallurgy chemical compound coating, that too went away... in the mean time, running E0 solved it... 

we aren't talking months, here, we're talking weeks that stuff attacked that engine. I can't imagine what it would have done had i just let it go.  

69fastback

So I just had to do some weed whacker maintenece and thought of this thread. I’ve had a Stihl FS90R for about 15 years, near as I can recall. I’ve ran e10 with Maxima 927 oil it’s whole life. I never use stabilizer and I’ve never drained it over the winter or anything. Just put gas in it, use it, hang it back up, and repeat. Never even put a plug in it. 

Well, 2 days it wouldn’t start, and it always starts in 1-2 pull. Always. This time it wouldn’t even try, and on a quick inspection I noticed the primer bulb was cracked. Easy enough. I ordered one that showed up today, but I decided to go ahead and remove the carb for a cleaning since it’s never been touched, and mostly I was bored. After all the e10 had been burned in it, it was a complete waste of time to pull it and clean it. Everything was spotless. Not even a speck of anything in the fuel screen. Put the new bulb in it, put it all back together and it started on the first pull. Good for another 15 years of e10 useage 👍

212rowboat

funny, @69fastback , the el cheapo husqi weedeaters and leaf blowers purchased at box stores (not REAL husqi's- the real deal 'not made under license' husqi's are fine machines) are NOT equipped to handle ethanol... i've replaced bulbs and lines almost every year while using those, and then finally just buying a 'good' one from a licensed dealer... 

i tried to order a carb kit for a leaf blower including the lines and bulbs, and was to be charged $65... i could buy a new one for $80!!!! so.... i stopped buying crap ones and went to the 'actual' ones- and have never had a problem. 

engineered to fail.... planned obsolescence... grrrrrrrrrrrr............

and while i'm on the subject, i helped a buddy remount his 2006 HDPI 2stroke yamaha 300hp outboard a few weeks ago (huge thanks to @Alswagg for the info/help!!!) and found there were literally 2 sets of head gaskets for those things in the entirety of North America... they are getting hard to find parts for... why? trying to push folks to newer engines, that's why... under copyright for a few more years- and by the time it expires there won't be any around...

planned.... obsolescence... 

212rowboat

Alswagg said:

212, you ran Ski Doos across the water? You said they were 265 hp?   What turbo company did you use?   I didn’t realize you had snowmobiles.  We have seen speeds top out easily in the high 90’s on some sleds while water skipping.  Our Yamaha Srx has a basic tune of 215 hp and tops out at 130 mph on packed snow.  That’s with a low boost.  Waiting to get full break in to bump up the boost and power output 

sorry for the mis-rep @Alswagg , they were Sea-Doo's not Ski-Doo's... these were the 155HP ones:


the 265's were a bit bigger and black.... and bright yellow.  black and bright yellow was hideous, but those things 'out of the hole' seemed every bit as fast as a yamaha v-max mc in the 1/8th mile... or even a hayabusa.... i'm talking no kidding 0-60 in under four seconds.. i said under four seconds..  they all but the 110hp top out about the same around 75mph (the 155 on E10 would only run 63~64ish, but every bit of 70 on E0).  i could (and did) pull skiers with both the 155 and 265, but the 265 would pull a slalom skier out as if they weren't even there. 

here is a funny about those that i learned later:  the displacement between the 130hp version and 155 is notta... the 155's have a bigger throttle body and tuned differently... the difference between the 130HP and the 210HP is the 210 is boosted (with larger injectors)... the 255HP was a boosted version of the 155HP (with still larger TB and injectors)... all four had different tunes.  the 265HP was a different animal pretty much altogether from what i understand, and i became frustrated with them as they liked to overheat....... i feel they did that is because the heat exchange (a plate on the bottom on all the models of that series) was the same. they handled the 130/155hp versions with ease- the 210 toed the line of usefulness- and the 255/265 models were under equipped for the energy created... the dash on those things would literally turn red (the bezel rings) and they would do nothing but idle- which is what you had to do keeping water flowing through them.   

insofar as ski's- i've a cabin outside of Iron River that has a trail run right beside it... those guys have some ridiculously built machines up there.  those things are so wicked fast it defies any expectation- a cousin of my wife also flies planes up there- has a landing strip at his camp in the watersmeet area... they drag race those things on that strip from time to time... i would LOVE to ride one of those, but.... I don't want anyone watching until i've figured out how to tame them. 

Michael T

.....and before I sold my Yamaha SVHO I smoked every Sea Doo on the water - they were so intimidated of that carbon black and chrome Yami monster that they would go out of their way to avoid us. Did have a couple of good runs with a Kawi or two.

212rowboat

Michael T said:

.....and before I sold my Yamaha SVHO I smoked every Sea Doo on the water - they were so intimidated of that carbon black and chrome Yami monster that they would go out of their way to avoid us. Did have a couple of good runs with a Kawi or two.

Most of the pwc's around here are rentals, and I've yet to see a rentor send a rider/renter out with either a red or black key but instead with only the yellow key... most folks won't know what that means, and most the renters/riders certainly don't.  I can promise you there is a big difference between those keys.

For those who don't know, the key used either restricts the tuning/governor, or unlocks it.  Yellow key limits both and red key unlocks both. 

Michael T

You could program speed/rpm limitations with a code right into the 2018 SVHO I had - was designed to keep your kids from killing themselves.