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So I've been using Ethanol Free(90 Octane) gas in my 2021 Roadmaster, but I feel like the fuel mileage is less, would I be better putting in premium 93 octane instead?
 

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Next fill up, tell yourself "this tank-full will have great MPG"..




And it will be so.. ( I feel like.)
 

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I'm probably wrong here but with my knowledge of modern engines, it doesn't really matter if you exceed octane requirements; it's moot. Octane only prevents pre-detonation, with some variables like advancing or retarding timing. If you were having pre-detonation issues, trust me you'd know about it; engine knock etc. I don't believe there's any gas mileage advantage to higher octane, though you could introduce some octane booster into your tank... but that's a mixed blessing because some of that stuff damages cats meow if you have them still installed. I'm not a 'cats' guy, I prefer parrots, so my cats will be uninstalled soon after breakin.
 

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Two things: First, use as high octane as you can, preferably non-ethanol. Second, avoid ethanol like the plague for sure if you're going to park it for any length of time. I've been in a tight spot before and used a gallon of 89 ethanol to get me to the next gas station and then filled up using no ethanol 91 rating. So... Indian recommends 91, and then "no ethanol" is the next most important thing.
 

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I would say “no ethanol” as the most important factor. Then is depends on how much ethanol is in the fuel. At one point ethanol was max 5%, Now some places are pushing 20%. 20% will damage the engine and I haven’t seen many stations say how much ethanol is in the fuel. I only have a few places I can go to get ethanol free and it’s 91 octane, so that’s what I get.

Before the crisis I put 90/89 in the bikes and did some comparisons of price/mileage/octane… and found it to average out. Better mpg but higher octane/price. Save $$ but get lower mpg. After all said and done, for me personally, it averaged out and I didn’t see much savings so I just do 91 now without giving it much thought. Did this experiment with the suv and I’m definitely sticking with 87 octane for the cage. For some reason it made a bigger difference for that vehicle.

Hope this helps. Stay safe, upright, and cool out their.
 

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I asked that question at the start of this month and was surprised (and pleased) how much response there was, perhaps I should ask about oil next . . .

Anyway, there is a lot of good discussion here.
 

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Ethanol gives less power so I always go for 5% or less plus Ethanol screws with the rubber seals and so forth in the engine, it's all BS at the end of the day as we shall see in due course 😉
What rubber seals? The Indian, like all fuel-injected bikes/cars manufactured in the last 20+ years are designed with materials that are compatible with ethanol. That includes all the seals and fuel lines.
 

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So I've been using Ethanol Free(90 Octane) gas in my 2021 Roadmaster, but I feel like the fuel mileage is less, would I be better putting in premium 93 octane instead?
Hey I was running Ethanol Free but every time I was traveling of coarse I didn't bother looking for it and just fill up with 93 octane. I found my 21 RM to be much happier, runs much better with 93 octane.
 

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What rubber seals? The Indian, like all fuel-injected bikes/cars manufactured in the last 20+ years are designed with materials that are compatible with ethanol. That includes all the seals and fuel lines.
My Indian is new, my other bikes are not. Ethanol has a lower calorific value than pure petrol (gas) therefore any percentage decreases available power/mileage. 👍
 

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US government requires all engines produced in the US and/or imported to be compatible with E10.

Personally I have never had access to "pure gas" and have never had issues related to it. I also have never seen ethanol issues in Indian, Harley or Honda forums.


I trust the engineers that built these engines to know what they can handle. Factory would not put stickers and notices in manuals saying the engines were E10 compatible if they couldn't. $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
 

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Your bike is engineered to use ethanol gasoline. Unless you’re buying a tank of gas and leaving it in your bike for a year +, buy the highest octane available.
Octane is only for preventing spark knock with high compression engines. It has no effect on storage capabilities.
 

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Simple answer if the bike detects pre-ignition (due to lower octane rating) it will pull (retard) timing and your efficiency will go down. Ethanol has less energy per unit mass than gasoline but has a high octane rating. I run ethanol fuel in anything with fuel injection. Anything with a carb gets ethanol free.
Pure gasoline has more energy per unit mass, but the bike can utilize the 93 with ethanol more efficiently so even with the lower specific energy you will get better performance including fuel mileage (compared to 90 octane pure gas).
 
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