ok so i was a moron but i did it for science lol
i tried to see if i could get similar performance and mpg if i used mid-grade gas and those cheap octane boosters/fuel additives but it didnt work. my milage dropped down to about 24 overall so i switched back to premium gas. ive put at least 8 gallons thru it since then but my mileage is still 23-24 with mainly highway driving. i know the winter drops my average by 1-2mpg but this is too much.
so my question is, should i wait for the car to straighten itself out or is anything i can do or check? i have close to 50k miles, is there any way to check the pcv valve besides goin to the dealer?

p.s. i know the mpg topic is beat to death but i just wanted to know what you guys thought

 

You know Ive run into the same issue on a trip in Colorado, i was forced to fill up with 89 because some of the mountain towns dont have a higher grade and my mileage has been low 20's since which is annoying because I usually average above 30mpg because of the altitude. Im convinved the ECU must try and compensate in some way as a failsafe or something to prevent detonation, maybe it takes a few tanks after? Check your basics (tire pressure, oil, air filter) as one of my tires was off a few psi over the summer and my mileage went to crap. As far as the pcv valve is concerned its relatively easy to change or check (less than a half hour to change) just search around for a DIY this forum has a great PCV one i used to change my own. Cheers!

Ian

 

don't use fuel or oil additives. good fuel and oil has enough detergents and other good things.

Top Tier Gasoline

 

iv gone thru about a full tank by now. i checked and filled my tires in mid dec. and im about 1200 miles from an oil change. and i changed the air filter at the end of summer. ill check everything out again and see if it will get back to my normal winter range.

 

MPG is calculated thru a formula.... there is no MPG sensor. Its never exact. Your going to drive yourself crazy looking for a problem that doesn't exist

 

i know there is no magic system or anything but i had a noticeable drop in my average and wanted to make sure everything was working properly and that there wasnt a serious problem.