MPGs Gone down since switch to syn oil

I have had my Taco for around 9k miles and when it was timed to change the oil I switched to Mobil 1. Ever since then my average MPGs went from 18.5 to 17, I keep track of all my fill ups. Has this happened to anyone and what have you done??? When I owned my previous car, 05 scion xb, I used restore Oil additive every oil change and noticed a bit of a difference in mpgs. Any thoughts, suggestions and comments are greatly appreciated!

 

Are you sure it's not winter blend gas or just stepping on the pedal heavier?

 

Did you switch to a different weight?

 

coincidence does not impute causality

 

There are so many variables involved it would be impossible to help with the information you have given.

A strong wind, hills, or number of passengers, bla, bla, bla, could probably give you a 1.5 mpg difference, good luck tracking that.

Keep an eye on overall fuel consumption trends and see if you have an issue over time.

If you have the discipline, keep a detailed driving log (towing, hauling, passengers, weather, topography, speed, temp, season, city, highway, fuel brand...) and maybe you can identify an issue that will cost you 1.5 mpg.

I keep a very un-detailed spreadsheet of every fill up and have see a varation in fuel consumption of 4.4 mpg and it does not really concern me. I am averaging 20.4 mpg over every fill up since I bought the truck and that works for me.

 

Switching out the rear diff flluid to synthetic makes a HUGE improvement.

 

It's probably winter blend gas that's causing it

 

I just did my first oil change and I have kept track of every fill up. I changed my oil at 5K and I noticed a 1 mile increase since I put Mobil 1 in.