Nolongeramember Posted October 3, 2018 Share Posted October 3, 2018 3 hours ago, Fab1 said: Engines need higher compression for higher combustion pressures/tempretures to make use of higher octane fuels.That's why cars with turbos,superchargers etc run high octane fuels as they have the above mentioned to adequately ignite the fuel in these conditions. If you run higher octane fuel in a car/outboard designed to run on a lesser octane fuel your doing more harm than good and throwing money away. Cheers. It’s actually the other way around. The turbo and high compression engines need higher octane fuel for a controlled burn and to not detonate. (Super high pressures and engine damage) They don’t need it to adequately “ignite” the fuel. It’s not like other engines won’t ignite the high octane fuel as you say. They will. But higher octane fuel burns in a more “controlled” manner. It is less prone to detonate and damage the engine and can handle high pressure better. Many people think that higher octane means more explosive. It’s not! It just burns in the engine in a more controlled manner, thus avoiding/ less chance of detonation/ damage. If your engine needs it, use it. If it doesn’t then don’t. Simple. 1 Link to comment Share on other sites More sharing options...
Fishop Posted October 4, 2018 Share Posted October 4, 2018 14 hours ago, Hateanchors said: Just to add, there is no harm in using higher octane than you need. Just the price. I use 95 sometimes even though I only need 91, but I don’t want to use ethanol 91 so rather pay for 95. I use caltex as its the closest one in town and I get woolies rewards points and a 4c discount...lol. But the caltex website says the 95 has "cleaning agents" in it to help with crud buildup in the engine. Which the 91 does not. So thats another reason why I use 95 its only 8c/L or so more expensive. 1 Link to comment Share on other sites More sharing options...
big Neil Posted October 4, 2018 Share Posted October 4, 2018 19 hours ago, Hateanchors said: Just to add, there is no harm in using higher octane than you need. Just the price. I use 95 sometimes even though I only need 91, but I don’t want to use ethanol 91 so rather pay for 95. So is the advice which I've been given correct? DO NOT USE E 10 in outboards. Okay to use 95 or even 98 instead of unleaded 91 (just costs more). RSVP, bn 1 Link to comment Share on other sites More sharing options...
GoingFishing Posted October 4, 2018 Share Posted October 4, 2018 (edited) 1 hour ago, big Neil said: So is the advice which I've been given correct? DO NOT USE E 10 in outboards. Okay to use 95 or even 98 instead of unleaded 91 (just costs more). RSVP, bn In Sydney you can get 91 octane fuel without ethanol.....and 94 with ethanol. I assume if you live in an area that doesnt have 91 octane fuel without ethanol then your only choice is to use 95 or 98 Edited October 4, 2018 by GoingFishing 1 Link to comment Share on other sites More sharing options...
Berleyguts Posted October 4, 2018 Share Posted October 4, 2018 22 minutes ago, GoingFishing said: In Sydney you can get 91 octane fuel without ethanol.....and with ethanol. I assume if you live in an area that doesnt have 91 octane fuel without ethanol then your only choice is to use 95 or 98 I’m pretty sure that E10 is 94 octane. @big Neil - The main issue with ethanol fuels is allegedly that they attract moisture. Being plant based, it also allegedly has a natural moisture content. It is also alleged that it eats rubber fuel lines. Having owned a VW Kombi (miss it every day), where the fuel lines are above the engine, this is a big no no! Too many Kombis and beetles go up in smoke from leaking fuel lines - check the fuel lines regularly and change them yearly! Funny thing is though, when I was in Hawaii, I hired a Camaro convertible and was told at a servo that the only fuel available there was E10. Go figure! 2 Link to comment Share on other sites More sharing options...
dunc333 Posted October 4, 2018 Share Posted October 4, 2018 hi gone fishing ,yes you are right. the best thing i can recommened is read your outboard workshop manual or operation manual as every outboard is differrent and manufactures will recommened what is best for that engine you have and go from there easy as that 1 Link to comment Share on other sites More sharing options...
Nolongeramember Posted October 4, 2018 Author Share Posted October 4, 2018 4 hours ago, big Neil said: So is the advice which I've been given correct? DO NOT USE E 10 in outboards. Okay to use 95 or even 98 instead of unleaded 91 (just costs more). RSVP, bn Use what the engine manufacturer recommends. If they say E10 is OK then use it if you want. I always stay away from it personally. Yes it’s ok to use 95 or 98 instead of 91. No harm done at all, but if all you need is 91 you are wasting your money. Some people say they get better mileage with the higher octane but that’s for you to test and decide if it’s worth it. 1 1 Link to comment Share on other sites More sharing options...
Nolongeramember Posted October 4, 2018 Author Share Posted October 4, 2018 9 hours ago, Fishop said: I use caltex as its the closest one in town and I get woolies rewards points and a 4c discount...lol. But the caltex website says the 95 has "cleaning agents" in it to help with crud buildup in the engine. Which the 91 does not. So thats another reason why I use 95 its only 8c/L or so more expensive. Personally I don’t believe any of that marketing. If you can use 91 then I wouldn’t pay extra for 95. Link to comment Share on other sites More sharing options...
Berleyguts Posted October 4, 2018 Share Posted October 4, 2018 21 minutes ago, Hateanchors said: Personally I don’t believe any of that marketing. If you can use 91 then I wouldn’t pay extra for 95. In my car, I definitely get better performance with 98 compared to 95. I haven’t used 91, so I can’t compare. On a highway trip, I get 100km more to the tank with 98, compared to 95 and it seems to have more get up and go. I will try and do some comparisons in the boat but sea conditions will probably impact on results. I tend to go everywhere flat out or as fast as conditions will allow except when trolling or approaching a spot. ? 1 Link to comment Share on other sites More sharing options...
Fishop Posted October 5, 2018 Share Posted October 5, 2018 15 hours ago, Hateanchors said: Personally I don’t believe any of that marketing. If you can use 91 then I wouldn’t pay extra for 95. Yeah I guess. Caltex has 91 unleaded (no ethanol) just looked today its actually 12c/L more but thats still only 12 bucks a full tank. And I would go through a tank once a month if I am lucky. The merc manual says to use minimum 90 RON fuel. Link to comment Share on other sites More sharing options...
Berleyguts Posted October 5, 2018 Share Posted October 5, 2018 And go... 1 Link to comment Share on other sites More sharing options...
jeffb5.8 Posted October 5, 2018 Share Posted October 5, 2018 95 as it’s easy to pull up against at my local BP. Mid range between 91 and 98. only use BP where possible as be told two strokes and high reving motors which use Shell have varnishing on the plugs earlier and reduce plug life. Will try BP 91 now the sevice station near me has had new tanks and pumps installed. 1 Link to comment Share on other sites More sharing options...
fragmeister Posted October 5, 2018 Share Posted October 5, 2018 Is this a two stroke topic? Cheers Jim Link to comment Share on other sites More sharing options...
Nolongeramember Posted October 5, 2018 Author Share Posted October 5, 2018 I use 91 non ethanol. My outboard does not need anything higher and I don’t see anything worthwhile to gain from paying more for higher octane. If 91 is not available I’ll use 95 as second choice. 2 Link to comment Share on other sites More sharing options...
Berleyguts Posted October 5, 2018 Share Posted October 5, 2018 2 hours ago, fragmeister said: Is this a two stroke topic? Cheers Jim Nope. It’s a fuel topic, started so @mrsswordfisherman can merge in the off topic posts re fuel that we put in the thread on outboards. ? There was a lot of discussion on the different octane of petrol used. Shouldn’t matter if it’s a 4 stroke or a 2 stroke motor but feel free to state what motor it’s going in. I hadn’t factored in diesel, though! ? 1 Link to comment Share on other sites More sharing options...
JonD Posted October 5, 2018 Share Posted October 5, 2018 What the manufacture recommends in my Yam f70 unleaded 91, this is what every outboard mechanic I've spoken with recommend. 2 Link to comment Share on other sites More sharing options...
antonywardle Posted October 5, 2018 Share Posted October 5, 2018 I had been using 95, and the main reason for this is that the servo where I fill up. The lane that I chose i has E10, 95 or 98, but this lane is the easiest to get the boat in and out of and the filler cap is on that side. Yesterday, I just took down jerry can and filled that up with 91. I always carry a jerry can on board, and when I am topping up the tank, I like to use the jerry can first so I'm not carting around older fuel for too long. I've I don't use it for a whle, it goes in to the lawn mower. 1 Link to comment Share on other sites More sharing options...
JonD Posted October 6, 2018 Share Posted October 6, 2018 I read somewhere that the bigger 250 Suzuki's need 98 yet talking and viewing a good friends new ( secondhand) dive boat with twin Suzuki 300's he's been told 91 by the mechanics and previous owner. 1 Link to comment Share on other sites More sharing options...
mrsswordfisherman Posted October 6, 2018 Share Posted October 6, 2018 OK guys I have merged the comments from the other post but they will not be in logical order. Lets keep the discussion in here - I can delete anything if needed 1 1 Link to comment Share on other sites More sharing options...
PaddyT Posted October 7, 2018 Share Posted October 7, 2018 Most fuel on the east coast comes from overseas (Singapore), so what you get at one servo is the same as any other, most outboards are fine with 91, its just that 91 without ethanol is hard to find. I tend to use 95, most fuel problems occur from contamination at the servo itself. 1 Link to comment Share on other sites More sharing options...
fragmeister Posted October 8, 2018 Share Posted October 8, 2018 (edited) My Yamaha 150 4 Stroke (5 years old) says I should use 98 so I do... never really gave it a thought until now. Edited October 8, 2018 by fragmeister Link to comment Share on other sites More sharing options...
GoingFishing Posted October 8, 2018 Share Posted October 8, 2018 52 minutes ago, fragmeister said: My Yamaha 150 4 Stroke (5 years old) says I should use 98 so I do... never really gave it a thought until now. When i made my original comments Jim it was to alert ETEC owners that they should be using 91 octane fuel as per Evinrude user manual. If your manufacturer recommends 98 id be sticking with that, as that was the essence of my original post. Link to comment Share on other sites More sharing options...
dunc333 Posted October 10, 2018 Share Posted October 10, 2018 i just got word today that america is now producing e15 .I hope it doesnt happen here as e10 is rubbish for most marine engines 1 Link to comment Share on other sites More sharing options...
Fishop Posted October 10, 2018 Share Posted October 10, 2018 On 10/4/2018 at 5:40 PM, dunc333 said: hi gone fishing ,yes you are right. the best thing i can recommened is read your outboard workshop manual or operation manual as every outboard is differrent and manufactures will recommened what is best for that engine you have and go from there easy as that Ethanols fine, what are you worried about? From the mercury website QUESTION: Will the use of fuels containing ethanol void my engine warranty? ANSWER: Fuels containing up to 10 percent ethanol are considered acceptable for use in Mercury engines. Fuels containing higher levels of ethanol are not considered acceptable for use, and the use of fuels containing ethanol higher than 10 percent can void the warranty. Link to comment Share on other sites More sharing options...
raging Posted October 10, 2018 Share Posted October 10, 2018 Don’t use ethanol. It absorbes water. Just use non-ethanol at the octane rating your motor is tuned for. 1 Link to comment Share on other sites More sharing options...
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