I've been riding Old Blue a while and never noticed any mileage differences between brands, but I've never used an ethanol blend, which would certainly reduce mileage and performance. On this bike, speed and ambient temperature cause mileage to vary greatly. I average 46 in town, and usually the lower-to-mid 50's on the backroads. Interstate speeds above 70mph reduce it into the mid-to-upper-40's. The lowest I've gotten is 42mpg (75-80mph with 20mph headwind) and the highest 63 (slow ride on the backroads with a nice tailwind). Mileage in winter is lower, as expected, and higher without the windshield.

Sometime back, Consumer Reports did mileage tests using different grades of gas, and the results were that mileage was not significantly affected by grade as long as detonation was not evident. Engineers I've spoken with (very large local refinery) tell me there is no advantage to using a grade higher than one which suppresses detonation. I have Old Blue's Crane ignition set to the highest advance curve, and usually use 93 octane since loading the engine with a lower grade causes detonation. However, at consistent speeds without loading the engine it'll tolerate the middle grade (89 octane). I've wondered if lowering the advance curve to use medium-grade gas under all conditions would reduce mileage enough to negate any savings by using a lower grade. I always fall back on the "if it ain't broke...." principle, though. Setting to a lower curve would reduce part-throttle performance, but not likely full-throttle, and might increase operating temperatures a bit. Anyone do any tests along these lines?

 

Glad to see someone else has very similar results with using different brands of gas. I do get better mpg's with Mobil but since the Sunoco is closer I use Sunoco. I have experienced even less mpg's with Shell.

 

Somebody tell me how to accurately measure the fuel usage (MPG if you will) of any vehicle without using a spreadsheet over time.
Even though this thread started back in 2006, nobody has ever answered it.

 

You should always use the lowest octane fuel as possible. If you notice any detonation go to the next grade of fuel. High test fuel usually contain more additives and will cause more buildup behind valves and in the combustion chamber.

 

Old thread , I get a difference using Gulf or Valero compared to Murphy USA and Shell.
31-33 with Shell ,36-38 with Valero or Gulf

 

I use an app called fillup. You put in your mileage, cost, and gallons at each fill up and it calculates the MPG'S. It will display a log off all your full ups, it will also show you a summary by month, 6 month, or year. My 14 limited averages 38 on the 10% ethanol blend (91) premium and 43 on ethanol free (91) premium. I haven't noticed any noticeable difference between brands.

 

Is that an iPhone app ? I have been calculating using mileage divided by gallons used.
Not very accurate but close.

 

I don't have an app. I've done this the old school method since I first started driving. I shouldn't be doing math in public so maybe it is time I get the app.

Anyway, to calculate MPG:

1. Fill your tank full of gas.
2. Reset trip odometer to 00000.
3. Ride.
4. Return to the gas station and fill the tank to full.
5. Note the number of gallons used to fill the tank. (Usually about 5.5 for me.)
6. Also, note the number of miles you rode via the trip odometer. (Usually about 210 for me.)
7. Calculate. Divide the miles driven by the gallons used: 210 by 5.5 = 38.18 MPG
8. Reset trip odometer; repeat.

If you don't have a trip odometer, you'll have to keep track of beginning and ending mileage to determine your distance traveled. But that involves more math.

Hope this helps.

 

+ 1, I use this method but I am lazy and apps are cool

 

I got it off the Android Play Store for my Samsung Galaxy S5. It's a free app. I just checked the Apple app store and the Fillup app isn't listed. But I did see an free app called myFuelLog Lite that looks similar to what I use.