What is the most optimal refuelling in the championship mode in the first level?

Track 1 (2 laps):
You can cross the track without refuelling.

Track 2 (1 lap):
You can cross the track without refuelling.

Track 3 (1 lap):
On the last station get fuel only above red line.

Track 4 (4 laps):
In the second lap get maximum fuel and you don't need anymore.