If it'll run on 87, but 91 is recommended . . . what happens if you put in 93?

[Ripper]

I have also found 89 octane is cheaper if you "blend" your own versus pumping 89 at the pump.

My understanding is that in most/all cases 89 is blended by the pump. Looks like "extra" profit by the station if you don't take into account the increased cost of a pump that can blend the gas.

 

[Quint]

My understanding is that in most/all cases 89 is blended by the pump. Looks like "extra" profit by the station if you don't take into account the increased cost of a pump that can blend the gas.

True, but I am pretty sure that the cost of that blending pump is paid for many times over.