noob question here, my car is an xray xb8, I did the break in with 20% nitro and 16% oil byron race gen2, after break in and one race I end up with almost a bottle of fuel left, but in my hobby shop i bought the last galon left byron race gen 2 but it is 20% nitro and 12% oil, should i mixed them? or should i finish first the 16% then start with the 12%, if so how do i prepare or what should i keep in mind for changing fuel

thanks in advanced