Wintermute
Member
Looking up the 2004 Mazda6 owner's manual there are two different schedules. One at 4 months/5,000 miles and one at 6 months/7,500 miles. Not sure why they have two on there.
That is because there are two service intervals for the car, based on your average driving conditions. The shorter interval is for "severe" conditions: Hot weather, dusty conditions, heavy stop and go traffic, aggressive/spirited driving. The longer interval is for "normal" conditions (i.e. you don't live in the desert and you don't spend 4 hours a day doing 10 mph spurts in traffic jams).
Most modern cars have this.