Every schedule will list explicit maintenance procedures that should be performed at a certain mileage or time interval, whichever comes first. If an interval states that an oil and filter change needs to be performed at 5,000 miles or 6 months, it means whichever comes first, the 5,000 miles or the elapsed time of 6 months.
As an example if the vehicle has 3,000 miles since the last maintenance visit but it’s been over 6 months, the next service should be performed.
To help the car owner keep track of their scheduled maintenance, Jenkins Auto Repair Professionals will place a sticker in the inside upper left corner of the windshield that lists when the next service should be performed. Most factory schedule booklets also provide an area where the car owner can record each service performed.