Which petrol in a four stroke
Printed From: The Fishing Website
Category: Saltwater Fishing
Forum Name: The Briny Bar
Forum Description: The place for general chat on saltwater fishing!
URL: https://www.fishing.net.nz/forum/forum_posts.asp?TID=86211
Printed Date: 16 Jun 2026 at 4:58am
Topic: Which petrol in a four stroke
Posted By: of2fsh
Subject: Which petrol in a four stroke
Date Posted: 23 Dec 2012 at 5:31pm
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Been running 98 in my new fourstroke 60 hp merc,do i need to or is 91 ok ? ------------- 2009 and 2010 BERKLEY SOFTBAIT COMP CHAMPS,Runner up 2013 ( solo),winner 2013/14 longest kingfish nz fishing competition |
Replies:
Posted By: Moggy
Date Posted: 23 Dec 2012 at 5:35pm
what does the handbook for that motor say? Like cars there are sometimes good reasons why 98 is used ------------- People who say it cannot be done should not interrupt those who are doing it! FISH FIGHT The Peoples Protest |
of2fsh wrote:Posted By: of2fsh
Date Posted: 23 Dec 2012 at 5:58pm
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Good idea...ill go find it ------------- 2009 and 2010 BERKLEY SOFTBAIT COMP CHAMPS,Runner up 2013 ( solo),winner 2013/14 longest kingfish nz fishing competition |
Posted By: bazza
Date Posted: 23 Dec 2012 at 6:08pm
If all else fails ... read the instructions. ------------- When you cry, feel pain or sadness, no one notices your sorrow .... BUT fart just ONE time !!!!!!!!!!! |
Posted By: Saltiga
Date Posted: 23 Dec 2012 at 6:30pm
| 91 in our 225 four stroke |
Posted By: bazza
Date Posted: 23 Dec 2012 at 6:53pm
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Have often wondered the same thing with the 90 hp merc which states it should be run on 95 or higher. I would assume using a lower octane would simply reduce the power but the dealers advise against it but do not give a good reason why. Presumably the only reason for wanting to run a lower octane than recommended would be because of it costing less or it was all that was available or in my case years ago, because a business related vehicle used a lower octane but best we don't go there. OK if a lower octane is all that is available then I doubt it would cause any damage but maybe someone that knows more about it would like to comment. As to if using a lower octane because it costs less may well be false economy if the reduced power required more fuel but once again will bow to qualified opinion. As to the other unspecified option .... reckon that brings its own risks but over to each individual to decide. ------------- When you cry, feel pain or sadness, no one notices your sorrow .... BUT fart just ONE time !!!!!!!!!!! |
Posted By: of2fsh
Date Posted: 23 Dec 2012 at 7:01pm
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Manual says 90 octane minimum as long as its unleaded ------------- 2009 and 2010 BERKLEY SOFTBAIT COMP CHAMPS,Runner up 2013 ( solo),winner 2013/14 longest kingfish nz fishing competition |
Posted By: F1SH3N
Date Posted: 23 Dec 2012 at 7:01pm
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The spec's on the merc web site state 87.. Recommended Fuel 87 octane/up to 10% ethanol http://www.mercurymarine.com/engines/outboards/fourstrokes/40-60/" rel="nofollow - http://www.mercurymarine.com/engines/outboards/fourstrokes/40-60/ imho it can be a false economy as you go further in your car on 95 than 91 due to the more bang for your buck... |
Posted By: Rob Optimist
Date Posted: 23 Dec 2012 at 7:01pm
Do not under any circumstances read the instructions, you will find all sorts of complicated things to do and also worst of all your wife will tell you..............I told you so ------------- "attitude is everything" |
Posted By: Richard34482
Date Posted: 23 Dec 2012 at 7:04pm
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Also watch the brand of fuel you use, cheaper ones can be at a minimum on Octane rating, whereas big brands ie BP or Z will be on the money |
Posted By: of2fsh
Date Posted: 23 Dec 2012 at 7:17pm
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Thanks for the answers,next question ,engine does 6000 rpm,still running in so only been up there once or twice .while breaking in ive been running around low to mid throttle ( done 7 hours now so cruising at 3500 rpm up to max 4200 rpm) with varied throttle settings,when its run in what is a maximum rpm to cruise long distances ? ------------- 2009 and 2010 BERKLEY SOFTBAIT COMP CHAMPS,Runner up 2013 ( solo),winner 2013/14 longest kingfish nz fishing competition |
Posted By: bazza
Date Posted: 23 Dec 2012 at 7:44pm
Hey Wayne .... shouldn't you be asking these sort of questions of the supplier or agent ? Reckon if you had a disputed warranty claim as the result of possibly having done the wrong thing, then they are unlikely to be very sympathetic when you say " But someone on the forum told me that was the right thing to do!" ------------- When you cry, feel pain or sadness, no one notices your sorrow .... BUT fart just ONE time !!!!!!!!!!! |
Posted By: of2fsh
Date Posted: 23 Dec 2012 at 7:49pm
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Yes i have and are running it in via the correct procedure,however as ive found out in the past these can be on the conservative side,and theres plenty of people on here that will have genuine info that ay help...cant hurt to ask Bazza ------------- 2009 and 2010 BERKLEY SOFTBAIT COMP CHAMPS,Runner up 2013 ( solo),winner 2013/14 longest kingfish nz fishing competition |
Posted By: Kevin.S
Date Posted: 23 Dec 2012 at 8:06pm
| When I spoke to a dealer about fuel for my mercruiser I was going to use 91, because that is what the handbook says. But he said to use 95 to make sure the octane rating was high enough. If you use 91 and there is any determination in the fuel it will be too low. But using 95 you should be guaranteed at least 91. I suppose that depends how long the fuel sits in your tank, or the tank at the petrol station. |
Posted By: TIN TUB
Date Posted: 23 Dec 2012 at 8:14pm
not sure what the instruction says but I just clicked over 2116 hours in 4 and 1/2 years and has all been on 91 and motor is in perfect shape according to the service man who see's it more than his wife he told me ------------- ther ain't nothin' in the world a t-bone shuffle wont cure. |
Posted By: Bounty Hunter
Date Posted: 23 Dec 2012 at 8:24pm
careful - thats a north american website and they measure anti-knock properties of fuel as PON - which is about 4-5 units lower than the rest of the world which quotes it as RON. outboard manufacturers tune their motors to run on american gas - which is around 91RON - simply because thats the largest market. so 91 fuel is fine. modern efi outboards include knock-sensors which will retard the ignition if lower octane fuel is causing uncontrolled detonation. improved engine output from 'hi-octane' fuel will only be realised if the ignition timing is advanced - so in essence you need to tune the motor to the better fuel ------------- No disintegrations! |
Posted By: of2fsh
Date Posted: 23 Dec 2012 at 9:19pm
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Thanks for that,ill use 96 till its well and truly run in,did you guys run the motors in according to the manual ? ------------- 2009 and 2010 BERKLEY SOFTBAIT COMP CHAMPS,Runner up 2013 ( solo),winner 2013/14 longest kingfish nz fishing competition |
Posted By: Capt Asparagus
Date Posted: 23 Dec 2012 at 9:32pm
| I dont know about the octane stuff, I just know you should avoid ethanol added fuels like the plague, as they chew the guts outa of your motors soft bits, seals etc, or so my mechanic tells.... and has shown me on a motor he was servicing. so....no Gull gas I think.... |
Posted By: cirrus
Date Posted: 23 Dec 2012 at 11:24pm
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if using 91 octane as i have done with a 4 stroke honda,what brands do you prefer and why. Are any brands better than others,as regard reliability of said octane rating. |
Posted By: Jet_ski_fisher
Date Posted: 24 Dec 2012 at 1:53am
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gull have 91 and 10% gas, i use 91 will go higher octane when i suss out a 4 stroke, as this stops the detanation or pinging you hear. as it's two stroke i'll run 91 for now.. ------------- http://www.legasea.co.nz" rel="nofollow">  MH... Catch measure release...<*))))< |
Posted By: Ab_Fab
Date Posted: 24 Dec 2012 at 7:39am
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Hi Wayne, Have the same motor. Personally I use 96, largely because the boat lives at the bach so can sit for a while. Also followed the run in according to the manual and that seemed to work fine. Now I typically cruise up to about 4500rpm as the maximum for long distances as that seems to be the sweet spot for speed and economy. Motor is sitting on a Stabi 459 Cheers Ab ------------- What will a blonde girl say when you tell her she's pregnant? A: is it mine? |
Posted By: of2fsh
Date Posted: 24 Dec 2012 at 8:26am
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Cheers Neil,good info there,4500 rpm will be 27 mph cruising speed which is mint ------------- 2009 and 2010 BERKLEY SOFTBAIT COMP CHAMPS,Runner up 2013 ( solo),winner 2013/14 longest kingfish nz fishing competition |
Posted By: bluesignature
Date Posted: 24 Dec 2012 at 9:51am
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i use 91 if the boat is being used regularly but if it hasnt been used for a while will top it up with a higher octane also if coming into a period were i know it wont be used as often will use 95 that way you will keep the octane up and expences down as octane will drop over time |