[Brentco]

Originally Posted by Formulajones

I'm surprised California does that since the winter grade formulation really shouldn't be needed in the warmer climate where you aren't seeing much seasonal change.

We had it in Ohio and it wreaked havoc on our cars. Usually in February or March when we would have those freak warm 70 degree days and they weren't switching to summer grade till April. The car would buck and carry on until the next day when it was 20 degrees again, lol. Once the summer grade came along all was good.

Now living in Arizona, which is basically a similar climate to California, although maybe warmer at times, I haven't noticed any issues with the possible different formulations of winter or summer fuel which has led me to assume Arizona may not be doing that. Even during our colder months we can have 50 during the day, and I can drive down in elevation where it's 70-75 degrees and the car runs fine. No more Ohio symptoms

I may dig more into that and see what Arizona is doing because I'm almost certain we get our fuel supply from the same supplier as California.

Yeah apparently summer blends are more expensive to manufacture, and that has the greatest effect in California, because California has the strictest standards for reformulated gasoline. So I’m sure the oil companies want to keep the summer period as short as possible, regardless of whether a winter blend is actually needed in the winter months.

Map showing the federal requirements, and an interesting read at the link below. States and counties impose their own requirements on top of these, so the picture becomes even more complicated.

https://www.eia.gov/todayinenergy/detail.php?id=11031