Whats the actual recommend octane?

omniphil

Member
I'm in the USA and generally BMW bikes all recommend 89 octane. If I look for owners manuals online some of them also say 89 octane. The sticker on the bike says 87 octane.

I'm not one of those people who thinks premium gas is better and makes more power (it certainly doesn't) I'm one of those people who understands the need for the correct octane for the engine to perform optimally, but I'm finding conflicting info on what that octane is?

What are you folks not in the US supposed to run for gas?
 

Rooltje

New member
I'm in the USA and generally BMW bikes all recommend 89 octane. If I look for owners manuals online some of them also say 89 octane. The sticker on the bike says 87 octane.

I'm not one of those people who thinks premium gas is better and makes more power (it certainly doesn't) I'm one of those people who understands the need for the correct octane for the engine to perform optimally, but I'm finding conflicting info on what that octane is?

What are you folks not in the US supposed to run for gas?
In Australia the recommended octane is 95, but I always refuel with 98 octane
 

Ceesie76

Active member
My Honda 300 scooter in France runs more efficient on lower octane gas believe it or not. It was commented on the Honda forums, I tested it out and sure enough. I have not tested it on the BMW but always fill up with the medium grade (89 I think here in US).
 

omniphil

Member
My Honda 300 scooter in France runs more efficient on lower octane gas believe it or not. It was commented on the Honda forums, I tested it out and sure enough. I have not tested it on the BMW but always fill up with the medium grade (89 I think here in US).
That is why I ask, because lower octane gas has more energy content and it makes sense that it would run better on lower octane. If the engine is setup for 87 octane, using 89 or 91/93 will actually make less power. Higher octane gas isn't better gas... (Unless your vehicle requires it)

The lowest octane gas that an engine can run without knocking is going to produce more power and better efficiency.
 

Claudini

New member
The higher the Octane the reduced chance you will get detonation at higher ambient temperatures. It is mid May here in Phoenix Arizona (U.S.A.), as I’m writing this, I’m putting in Premium gasoline, which here is 91 Octane. We are expecting today our 2nd day of temps greater than 100 degrees F. This June I’m traveling through the Sonoran desert where last year I got hit with a 117 degree F temperature while riding a BMW F700 GS. This year I’m trying it on my current BMW C400 GT. (**PRAY FOR ME**) The reason why you do not get better gas mileage on Premium here in North America is that the easiest way to increase Octane is to add more Ethanol. Ethanol has fewer BTUs per gallon. This winter I’ll go back to 89 Octane from the gasoline stations that carry it. Later this Fall I’ll let you know how the scooter fared under the abuse I plan for it.

v/r Claude
 
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Pappy13

Active member
I live near a lake (Jackson) and most of the boats run ethanol free gas, when I fill up close to the house I use the "Rec 90" ethanol free 90 Octane, the owners manual calls for 89 Octane lead free. A normal tank of gas will return 51.1 miles per gallon if I'm not blasting away from the traffic signals, I REALLY like the ethanol free for my air cooled engines (lawn tractor, pressure washer, 2 stroke equipment). In the earlier Jap bikes (CX650, VF700, VTX1800) I could REALLY tell a difference in the fuels, power and economy, with the C650GT, not so much. I'm very hands on with my equipment and since I've gone to ethanol free for my air cooled engines I've had NO fuel related repairs to make (cracked or soft and leaking fuel lines, gummed up carburetors, cranky starting), this may not do anything for the BMW, and I'll run the mid-grade gas if I can't get ethanol free, but it's what I like in my bike.........
 

Claudini

New member
Does anyone have the conversion factors necessary to convert RON to AKI and Octane as seen on US pumps?

v/r (very respectfully), Claude
 
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mjnorris

Active member
The owners manual on my 2013 650gt says 89 octane and living in Oklahoma I can get no ethanol at a lot of stations. Not so in Texas.
 

MatteOrange

New member
My manual notes regular grade gasoline.
91 ROZ/RON, 87 AKI (AKI is the US rating for octane).
Everything I came across in online or bike manual notes regular grade, the dealer is saying premium?
Do what the book says and you’ll never be wrong.
My 310 GS runs on regular, if I used anything higher it would stall when started. It could take up to 5 starts before it kept running. Started to use only 87 octane and it started perfectly and ran great.
Sometimes less is more.

I purchased the repair manual and the specs in this manual list using premium fuel min 90AKI.
 
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hannesd

New member
anyone having problems using fuel with 5-10% of ethanol on longterm basis?
in europe we don't have fuel without ethanol anymore.
on the fuelcap a sticker shows E5 and E10 so both of our fuel choices should be accepted.
still ethanol is known for attacing rubber and plastic parts of the fuel system...
 

janpoko

New member
Well I would suggest to use a fuel with ETBE (ethyl-tercbutyl-ether) instead of Ethanol, if there is an option. I have ridden 8000km on E10 with ETBE and so far no prob. Of course it is not enough km nor time to judge..
 

DrCohen

Active member
I'm in the USA and generally BMW bikes all recommend 89 octane. If I look for owners manuals online some of them also say 89 octane. The sticker on the bike says 87 octane.

I'm not one of those people who thinks premium gas is better and makes more power (it certainly doesn't) I'm one of those people who understands the need for the correct octane for the engine to perform optimally, but I'm finding conflicting info on what that octane is?

What are you folks not in the US supposed to run for gas?
The C650GT Rider's Manual says
"Recommended fuel quality Super unleaded, (max. 10 % ethanol, E10)
89 AKI (95 ROZ/RON)
89 AKI"
In the United States, the number on the pump is AKI ("Anti-Knock Index"). In the U.S., 89 AKI is normally sold as "mid-grade".
 

Hack2004

Member
I love this bantering back and forth. It reminds me of the on-going discussions on Advrider site about “What oil should I use?” Or. “What is the recommended tire for. …..??” Seems like there are a million or billion differing opinions. Keeps these sites interesting
 
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