I have a nice Italian motorcycle and the manual calls for 95 octane fuel. In the ten years I have owned the bike I have yet to come across 95 octane unleaded at a gas station anywhere in the country. So I generally put the highest available whether it is 91 or 93 or on rare occasion 94. My motorcyle has a 3.5 gallon tank and a .9 gallon reserve for a total fill up of 4.4 gallons.
As we all know most gas pumps commonly offer three blends of unleaded in different octanes. It has become the norm over the last 10 years for all three octanes to be dispensed from the same nozzle. Since the cutoff mechanism for the flow is at the nozzle, my assumption is that somewhere in pump is a mechanism that chooses which octane to pump. When I choose an octane, this mechanism changes which storage tank to pump fuel from. However, the hose going from that mechanism to the nozzle will still have the octane which the previous customer purchased. My question is, what quantity of fuel is in that hose between the nozzle and switching mechanism?
Because motorcycles have small tanks, if the last customer bought 87 octane fuel, and the hose contains 1 gallon of fuel and I select 93 octane and purchase 3 gallons, I’d really be getting 1 gallon of 87 octane and 2 gallons of 93 octane for a 3 gallon mix of 91 octane.
BTW, when I find gas stations that still have the older style pumps with a hose for each octane, I make a mental note and will frequent them when I can.
Where I live, there are quite a few gas stations that have a really long hose coming off the pump–easily long enough to reach to the opposite side of a truck that pulled in with the wrong side facing the pump. I wouldn’t be at all surprised if as much as 20% of the fuel I buy comes out at the wrong grade. You’re right, so far as I can tell, it seems we’re not getting what we pay for.
My solutions so far have been:
Try to find a pump where the last person bought premium. (Usually the last purchase is still on the pump.)
Use some octane booster from your local auto parts place.
Live with it. (Not my favorite.)
Same issue with most eurobikes. In Europe they use research octane only. In U.S. we use average of research and motor methods, which yields a lower number for a given fuel. Just buy premium and if you don’t hear it knocking you are fine.
One solution would be to bring a small gas can with you, and put about a gallon in it to make sure you are getting the good stuff into your motorcycle, and then put the gas from the can into your car tank, or other equipment you have. I know that this is not an optimal solution since motorcycles aren’t great for carrying a bunch of stuff around with them, and you’d pretty much just have to go right home to drop the can off since I don’t think you’d want to be riding around with a full gas can…
as has been mentioned, it most likely wants 95 RON (research octane number.) The done thing in the US is to use the average of RON and MON (motor octane number.) upshot is that a given fuel will have a lower (R+M)/2 octane number than a straight RON number, generally somewhere between 3-5 octane points. so 91 octane in the US should be close if not the same as 95 RON.
To complicate matters a bit, most stations now have only 2 storage tanks, 1 for regular grade and one for premium. The mid-grade, often called ‘plus’ fuel is mixed at the pump from a blend of regular and premium.
The fuel trucks only haul the 2 grades, regular and premium. For those stations that do not have the ability to blend mid-grade fuel at the pump, the delivery truck blends it at delivery.
IN the old days there was lots of slop in a gas station’s pumps. You could drain gas from a hose with the pump shut off. Today’s pumps have had major changes to deal with EPA regulations and fuel injected engines. The fuel metering is much tighter. You may only be talking about drops of crossover between customers.
Don’t accept my theory? Don’t. Test it for yourself. Next time you go for gas, put the pump handle over your inlet and open the flow before paying anything. You should see almost nothing coming out of the nozzle. This tiny amount, if any, is from the previous customer.
That accounts for what’s between the valve in the handle and the end of the nozzle. You still have the previous customer’s fuel that’s IN the hose (apparently a quarter of a gallon using Rick’s calculation) that you’re paying premium prices for.