Scheduling
Fleet → Maintenance → Schedule service. Schedule either by distance (every 5,000km, read from the odometer) or by date (every six months). FleetOS warns you as either threshold approaches.
Logging work done
Record the date, the odometer, what was done, the parts used and the cost. The cost feeds the vehicle's cost-per-kilometre figure, so logging it is what makes the economics real rather than guesswork.
Taking a vehicle off the road
Set the vehicle's status to In maintenance. It then cannot be assigned to new trips, which stops a dispatcher booking a van that is on a lift.
History
Every vehicle keeps its full service history on its detail page. This is what you hand over when you sell the vehicle, and what tells you whether a recurring fault has been seen before.