Odd MPG issue....

[houndguy]

I bought my 08 with about 2000 miles (3219 KM) on it roughly, in the 3 odd months that I've owned it I've placed 3,500 miles (5632 KM) on it.  I ride it mostly highway but in all types of weather.

Every now and again my gas mileage falls by 10 miles or so per gallon (4.3 KM/L).  I am generally in the mid 50's (23.3 KM/L)    Now I am not picky but usually buy gas at the same stations all the time.   I will get 3 or 4 full tanks at 55 mpg (23.3 KM/L) and then that drops to 45 mpg (19.1 KM/L) for a tank.  Then I'm back to 55 MPG (23.3 KM/L) for the next.

I ride the same roads on my commute, and maintain roughly the same speeds every night.  Ideas?  At first I thought it was just "a bad tank of gas" but it's happening in a pattern now.  Even if this issue is caused by  "seasonal" gas you would think it would be consistent???
 

[Vivo]

And how many times have this 55- 55- 45 happened Sir? Even though it seems you do things the same everyday, no two trips are the same... You might encounter a crosswind today, you might have overtook several cars, increased you speed yesterday, different air temperature, stopped at more stop lights, and like you said, some bad gas, etc. There are lots of un-noticed factors that may lead to different MPGs.

[sissy mary]

Head winds, riding at 70 instead of 65, a little more city riding can all bring down the MPG real fast.

[houndguy]

And how many times have this 55- 55- 45 happened Sir? Even though it seems you do things the same everyday, no two trips are the same... You might encounter a crosswind today, you might have overtook several cars, increased you speed yesterday, different air temperature, stopped at more stop lights, and like you said, some bad gas, etc. There are lots of un-noticed factors that may lead to different MPGs.

I hear you.

I thought about that too, but its happening enough to form a pattern now.   About every 5th fill-up my MPG drops.   I'm going to keep track of it using the Fuelly website, but missed a fill up yesterday (so much for scientific accuracy). 

[MotoRandy123]

Maybe your getting a bubble in the tank so not filling the same amount all the time?

[Vivo]

Hmmm....every 5th fill-up.... from 55 to 45.... lots of 5's there....

5 wounds of Jesus, 5 books of Moses, Muslims pray 5 times a day, 5 elements, the perfect 5th is the most constant harmony, we have 5 senses, there are 5 oceans in the world, Olympics has 5 rings, 5 players in a basketball game, five fingers... hmmm...     Keep us posted....

[sissy mary]

Since you get gas at the same place, maybe the owner plays with the gas pump setting every now and then? 10 miles per gallon makes no sence at all. The other 4 times your getting great MPG.

[BigOrange]

seafoam or stabil

[BigOrange]

What happened to the magical unicorn piss?

[Vivo]

What happened to the magical unicorn piss?

it evaporated...with Zombie...