Just recently, for about 3 tanks my mileage has increase from ~300 per 16 gallons to ~380 per 16 gallons. I have not changed my driving style. Does anyone have a hypothesis on why this may have happened? Could I have a knock sensor of MAF sensor that my have been acting up an no longer is?

I did switch form Mobile 1 to Castrol GTX (both 5W-30) 15K miles ago (82K miles on the car). I change my oil every 3-4K. I have noticed the performance of the car to be more consistent. Before switching I would experience bouts of sluggishness.

Could my engine not have been properly broken in prior to the switch (I switched to synthetic at 6K miles)? I have been getting Blackstone Analyses with both oils. The wear metals have read the same with both oils. This leads me to believe break in was not the reason.

My guess is the knock sensor was misbehaving.

 

Who knows. Fuel composition, weather changes, even your driving style may have (slightly) changed and you haven't noticed.

In any case, mileage threads suck and IBTL.

 

Why did you bother switching to synthetic if you're just going to use an archaic OCI of 3-4k miles...

 

Why bother posting if you don't read?

Synthetic --> Dino

 

Or gas went from crappy Ethanol blend to 100% gasoline.