[Turtles] What requires fuel?

In the time that I were used to mess around with computercraft turtles didn't require fuel. Now after some time I started messing around with computercraft again and found out about "fuel".
I searched around the wiki for a bit and couldn't really get an answer to this question:

What methods from the turtle API cost fuel to perform?

The wiki says: "The Turtle can move 1 block for each fuel count it has." Does this mean that turtle.turnLeft/Right() don't require fuel? And methods like: inspect, detect, compare, suck and drop don't require any fuel either?

I hope someone could make it clear!

you are indeed correct. only when a Turtle moves does it consume fuel. meaning you can rotate it or anything else, free of charge.

be aware though that some 3rd-party peripherals do consume fuel for their own tasks as well.

Thank you! Now I'm less scared to turn on fuel consumption :-P