Question about past "My Mileage Sucks" threads

[Loyal Toyota]

Is there any hard facts that the gas actually changes in winter? Why would they change the chemical makeup, like for what purpose?

Here are two good starting resources:
Winter Oxygenated Programs | Fuels & Fuel Additives | Transportation & Air Quality | US EPA

winter gas ? - Bob Is The Oil Guy

The gist of it is emissions, better start-ups, gas less likely to freeze, etc.

 

[RunninInGA]

Speaking of that I'm at about 32-34psi. Is that good or should I go a little higher ?

I like to run 36-38 in mine, but was running in the low 40s on my other cars with low profile tires.

 

[PitbullRescuer]

Let us know if changing the front o2 helps, I changed just about everything I could but the front o2 on my truck ....

Finally changed my upstream O2 sensor over the weekend. The one that came out was disgusting looking. Filled it up from empty right after I changed it out. Drove 148.8 miles, took 8.729 gallons to refill it = 17.05 MPG. (and I was driving like a bit of a douche yesterday morning, I was late) The tank I filled from empty on Saturday I got 14.46 MPG.

Conclusion, yes, it's worth it to change your O2 sensor if it's beat. Pretty sure mine was original so after 15 years and 191K miles, it was due.