Your engine requires the correct blend of fuel to
run at its optimum performance. The fuel companies
recommend which engines their fuel should be used 
with, and you should try to use the right kind of fuel 
for the engines you're running. If you can't manage 
this, you should use the highest quality fuel you can 
afford. The fuel companies can only support a limited 
number of teams each season, so you might not be 
able to enter into a contract with your first choice of
supplier.