verb form ir + gerundio

[Nfqufktc]

¡Hola!
I would appreciate it if you could clarify the following point for me:
The verb form ir + gerundio expresses the idea of a continuous action with a nuance that the action is developing gradually / little by little as exemplified in
1. Ese camión va perdiendo aceite.
That truck is leaking oil.
2. Voy conociendo Madrid.
I am getting to know Madrid (little by little).

On the other hand, I have the following examples (from dictionaries):
3. Voy caminando al colegio todos los dias.
I walk to school every day.
How is it different from Ando / camino al colegio todos los dias (presente habitual)?
4.¡Voy volando!
I’m on my way! / I must dash!
I'd say there is nothing gradual about my condition of being in a hurry.
How is it different from ¡Estoy en camino! Llegaré pronto! I’m on my way! I’ll be there soon?

Would you comment on the accepted usage for examples 3 and 4 vs examples 1 and 2?


Thank you.

[poli]

It's a stylistic choice. In most cases it + gerundio roughly translates to continues to+infinitive.
FYI: it is also common to hear seguir + gerundio to a similar effect.

Please note that I am a native English speaker with working knowledge of Spanish. A native speaker may have something to add.

[aleCcowaN]

Basically all four examples don't match the verbal periphrasis ir + gerundio, which describes dynamically some gradual or onsetting process.

Some basic examples

Voy mejorando con la rehabilitación , lento pero seguro (I'm progressively getting better with rehabilitation, at a slow but steady pace)

Los pasajeros tomaban sus equipajes de mano mientras el tren iba entrando en la estación (As the train entered the terminal, the passengers began to grab their hand baggage.)

Your examples

Ese camión va perdiendo aceite

no periphrasis here, the lorry is leaking oil as it moves

Ese camión va/anda/marcha/camina/avanza perdiendo aceite.

Voy conociendo Madrid

it doesn't make much sense as a standalone phrase

Estoy yendo de una entrevista a otra todos los días, y mientras tanto voy conociendo Madrid.

Voy al colegio todos los días (I go...)

Voy caminando al colegio todos los días (I walk...)

no periphrasis here either.

¡Voy volando! (I'll be there in a breeze! or, I'll be there asap!, Estaré allí en menos que canta un gallo)

no periphrasis.

[Nfqufktc]

Thank you, poli.

[Nfqufktc]

Thank you, aleCcowan.