Gasoline requirement Top Tier 91 Octane?????

[rfcbuf]

My 2019 owners manual calls for 91 octane gas that is TOP TIER rated. Neither of these (2) requirements are available in gasoline stations conveniently close to where I live. What do most owners use to keep the GX running as it should without gas containing the proper additives to keep the engine/valves deposits in check and eliminate engine knock?

[JD460]

Any 91 is fine. Top tier is sort of a scam according to most gas delivery truckers. They say they deliver it to all types of stations even though it may not be labeled as such. 

[RX400h]

I really like Shell premium. Their gas is used exclusively by Car & Driver magazine. 

[Bykfixer]

I lived near a tank farm in Greensboro NC for a time and each day Exxon, Shell, Texaco, Amoco, etc trucks all filled from the same gasoline tank day after day. I could not believe my eyes. It was like that time I found out santa clause was actually not real. 

It's when the truck places the fuel into the tank at the filling station where the so-called magic begins. The specific product is mixed in there. 

I do not know how it is done but there are brands of gasoline I get better fuel economy using. Not a lot but 15-20 miles extra a tank full. 

I prefer 93 octane in my car but if 91 is all there is so be it. 

[Warren Marshall]

The magic:   From the refinery, gasoline and diesel fuels are transported to terminals.

It is at these terminals that detergents and additives, are added, to formulate to produce high quality blends.

I tested my mileage with the various octane's when I 1st purchased my ES350.  The better the octane - the better the gas mileage.

One thing I really  noticed was the performance.  What a difference between 93 octane vs 88 octane.  (and the price difference)