Hi, yes there is an F service and most likely the needed service is necessary service but each service item should be evaluated and many of the services can be done at separate times. All of the service items do not necessarily need to be done immediately. The letter F only represents the amount of time estimated to complete the service, in this case 6 hours. It does not stand for any particular services. In order to determine which services are due the service items must be called up in the instrument cluster. You should discuss with the service adviser which services can be put off, if any. Click here for the procedure to call up the service items.
And click here for the corresponding service sheet.
Let me know if you have any questions.