No, but it is generally recommended. It will "get used to it" faster if you do. Otherwise, it may run somewhat less than ideal for the first tank of gas or so.
Sedan Revolution #103
focus in storage. hit a rock with the oil filter and locked it up.
gotta sort out a 351w 4 door fox first, then the focus gets a 2.5
commuting with a v6 5 speed mazda 6 wagon.