91 or higher Octane Fuel for Outboards

[Volvo]

Yes i know this has been done before :), and have to say i have been a fan of high Octane fuel in all my previouse outboards and havent had or noticed any issues with its use , but was told today that High Octane fuel should not be used in Outboards of today !!??..
Whats the overall opinion especially from those onboard who sell and service todays Outboards??..
Keenly interested in opinions or should i say Ädvice in this arena :)..

[up the creek]

for every 10 people who say use higher octane,, 10 say dont, as for mechanics advice,, once again some say yes some say no to higher octane, all i know is ive had 2 strokes, bikes, outboards, mowers for 30 years and i always used 91, as a kid it was cos it was all i could afford, and never had any problems. its the old saying if it aint broke dont fix it, and its cheaper to use 91,... unless your motor is pinging then maybe its the motor not the fuel that needs higher octane as mine have all been fine on 91 . i have always wondered how much the fuel industry has pushed the marketing for higher octane fuels just to take more money of us... so i will use 91 for now as its cheap it works and i dont need 2 extra miles or 10% more power blah blah. i just go cruising and come home on me 91 just fine.... thats my 2 bobs whos next ha ha..

[stevej]

shouldn't have been used in the past either unless the manual said so

when ethanol came in people were told to use premium as it didnt have it, now you can find 91 again without ethanol
unless your outboard has a sensor to adust timing to make use of the fuel then your wasting your money

some premiums have detergents which can disrupt oil adhesion in two strokes as well

[TheRealAndy]

So I was talking to my mate who works for a refinery a couple of weeks back. Asked him if they still ship higher octane fuels to the regular 91 pumps when they have excess 95/98 and are running low on 91. His answer was yes, they still do it but its far less frequent than it used to be.

So there ya have it, the only thing you know you are getting from the bowser for sure is that the fuel meets the minimum octane rating stated.

As I have said many times before, you are wasting your coin unless the manual states you should use a higher octane fuel,

[gazza2006au]

At one stage in my life i was young drove a V6 commodore didn't have a lot of money so i ran unleaded E10 i was getting like 265km's to a 65L tank it was unbelievable all these oily dots across my rear bumper it was the worse fuel economy i have ever had even worse than my VB 253 Commodore with the baby V8, that V6 commodore has made me never want to touch another commodore again even tho i owned 3 commodores over around 12 years strait

i went to a hyundai excel and used unleaded 91 loving life full tank lasted 2 weeks it was amazing $40 to fill up

now i have a Nissan X-Trail i bought it with a blown engine and i done all the labour of rebuilding it in my back yard i had great fuel economy when she had a fresh motor running 91 unleaded (no ethernol) i was getting 550km's to a tank but now she has 60,000km's on the engine and 3 years she's like an alcoholic on fuel ;D i probably get around 400km's to a tank on the91 unleaded i have never used that E10 crap in this car

one thing i must say is 7-11 has the worse petrol ever, i drive a manual and i need more RPM to maintain the same speed if i go to those small independent petrol stations and buy 91 unleaded my fuel last a much noticeable longer time and i use less RPM for the same speed it is very noticeable

as for my outboards, bikes, jetski,'s, lawn mower i run nothing less than 91 unleaded and nothing more , most defiantly no E10!!!!!

[catshark]

here i am at the pump wondering what number do i dump, E10, 91,95,98. so many choices its hard mate, its getting late and ive gotta state, E10 forget about, 98 too dear, 95 l'll think about, leaves only 91 its choice mate. Seriously though 91 is great but however modern engines now might need a higher octane rating for a cleaner burn , and more effiecent running. Correct me if im wrong but arent mercury verados supercharged engines, i imagine they would need 95 minimum.

As for the above analogy on car fuel usage, wowsers 265klm on a tank of fuel, fuel filter clogged up. ha ha seriously ive found if i run my V8 on less than 95 it doesnt like it at all,

Outboards l'll throw this in, if one were too own a outboard with say 999cc, and one with say 1499cc,would you expect the chap with the bigger capacity to run higher octane?

[stevej]

there was something wrong with your commodore plain and simple,you cant compare one car against another when using discussing fuel consumption a commodore v an excel is just an absurd comparison
e

ethanol has a lower calorific value so you have to burn more for the same bang some vehicles just don run well on it and some are ok and you dont notice the difference cause its so minor
why do you need more revs in your xtrail cause its a manual the older ones had the same final drive ratio between auto and manual

[Volvo]

Good reads :), what was quoted to me was that outboards arent meant to run on high octane fuels??.

[gazza2006au]

there was something wrong with your commodore plain and simple,you cant compare one car against another when using discussing fuel consumption a commodore v an excel is just an absurd comparison
e

ethanol has a lower calorific value so you have to burn more for the same bang some vehicles just don run well on it and some are ok and you dont notice the difference cause its so minor
why do you need more revs in your xtrail cause its a manual the older ones had the same final drive ratio between auto and manualIf
u want to nit pick it Steve i was comparing it on a percentage mate :) there were no problems with the VR Commodore it just chewed the fuel like no tomorrow the Commodore probably lasted 2-3 light days on $20 worth of petrol or even a trip from Fairfield to Cronulla and back for a squid fish use to cost $20-$25 a night in fuel this is when fuel would have been around $1.10-$1.20 just 3 blokes in the car no trailer or boat

the Excel being a 4 cylinder still averaged the same distance as the Commodore when new around 400km's to a tank however that thing ran on a oily rag a full tank lasted easy 10 days

it may appear the Excel is smaller engine capacity but when u look at it like this

Commodore 65L tank 6 cylinder 400km's
Excel 40L tank 4 cylinder 400km's

you catch my drift i was working on distance not horse power or weight

the X-Trail when using 7/11 petrol is poor performance i estimate my car to go thru at lease 30% more petrol however i mostly fill up from the one 7/11 and i tend to use the same pump, of late i have been trying to go a little further to a independent petrol station the fuel last that much longer it is very noticeable and its not just me my mother who drives a small 4 cylinder car and my cousin who drives a old Suzuki Swift have both said the petrol is much better there my cousin actually said the 7/11 petrol is aweful, the performance of my X-Trail increases so much i see the difference, my memory is really s.... but i am pretty sure i can sit in 3rd gear 3000RPM doing 80kph when i use the better fuel the same applies but the revs come down to around 2650RPM same gear same speed just my observations and this has happen a few times i have noticed it

catshark 91 is affordable and good all round fuel for me i am happy with the price most of the time ;D

[stevej]

not nit picking ,your telling your story ill tell mine

there was something wrong with your commodore or it was poorly maintained or had high mileage
I had 5-6 commodore wagons and sedans as company cars and they would all return 500-600km per tank around Sydney and up to 800km per tank if just pure highway kms and I was doing a lot o fkms they were sold at 90,000km which was about every 18 months, these were newer cars then a vr though 2000 onwards

some were a little worse with e10 91,i had a falcon au series 3 wagon which hated the stuff and would see 10-20% less km

Fairfield to cronulla Is 35km lets say 50km so 100km round trip
$25 /$1.20 is 21l
so your car was using 21l per 100km ie the car was not performing properly, even worse if you bring it back to a 70 odd km trip
early hyundais were around10l city driving and the vrs 11-12
again there was something wrong with that commodore or your driving style getting a extra 500kg of mass going

also the comparison between a excel you have to include weight the Hyundai was 900 odd kilos the vr was 1400 kg that's half a tonne difference

[swof63]

Gazza I think your Xtrail has a problem. If it’s a three-pedal manual gearbox, the relationship between engine revs and road speed in any given gear is fixed. It’s determined by the transmission gear ratio multiplied by the final drive ratio then moderated by the circumference of the tyres ie. the distance travelled per revolution.
You may have different throttle positions required to maintain a given road speed/revs in a given gear, but if the revs change for a given speed in a given gear then you have either slip in the system - most likely the clutch, or you are actually in a different gear. Best get that looked at. In an automatic with a torque converter the situation changes and slip is built into the system when not in lockup.


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[billfisher]

Well I think the worst thing that will happen if you use high octane fuel is you may be wasting money. You need a high compression engine to get any benefit and outboards are generally low compression. The main thing is not to use fuels containing ethanol.

[gazza2006au]

Gazza I think your Xtrail has a problem. If it’s a three-pedal manual gearbox, the relationship between engine revs and road speed in any given gear is fixed. It’s determined by the transmission gear ratio multiplied by the final drive ratio then moderated by the circumference of the tyres ie. the distance travelled per revolution.
You may have different throttle positions required to maintain a given road speed/revs in a given gear, but if the revs change for a given speed in a given gear then you have either slip in the system - most likely the clutch, or you are actually in a different gear. Best get that looked at. In an automatic with a torque converter the situation changes and slip is built into the system when not in lockup.


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I checked last night it was actually 3rd gear 60kph just under 3k rpm, 4th gear was 80kph just under 3k rpm however the revs go up to 3k when im running that one brand of fuel

[shakey55]

Back to original question. I have a Johnson Oceanpro 115hp (2 banger) and I’ve always run 95 octane without a problem.


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