Car requires 91 fuel but there's only 87, 89, and 93
I just bought a 2002 BMW 325xi and on the gas
door and in the manual, it says only to use 91 fuel.
In the area i live, there is only 87, 89, and 93.
Should I mix 89 and 93 to get 91 or is it not that
simple? Will it cause any damage to the engine to
put in the wrong fuel type?