Paramos en la gasolinera de la autopista para llenar el tanque.

Yes. Written paramos can be either:

• Present: paramos = we stop
• Preterite: paramos = we stopped

In speech, many speakers distinguish them by stress:

• Present: paRAmos
• Preterite: paRAmos (often very similar), but the context usually clarifies. In a narrative about past events, it’s understood as preterite.

Parar en is common for “to stop at/in a place” (focus on the location where you stop):

• Paramos en la gasolinera = We stopped at the gas station.

Parar a is less typical for this meaning. You might see parar para + infinitive for purpose (which is exactly what happens next in the sentence).

Using la can mean the speaker treats it as a specific or expected gas station in context—often “the one by the highway” mentioned immediately after. In real speech, both can work:

• Paramos en una gasolinera... = we stopped at a gas station (not important which)
• Paramos en la gasolinera... = we stopped at the gas station (more specific/identifiable)

It depends on the country. Gasolinera is widely understood, but in many places you’ll often hear:

• gasolinera (common in several countries)
• estación de servicio
• bencinera (common in Chile)
• grifo (common in Peru)
• bomba / la bomba (common in parts of Central America)

All can mean “gas station,” with regional preference.

Literally it’s of the highway, but in natural English it usually corresponds to on/along the highway or by the highway. In Spanish, de + place often marks association/location:

• la gasolinera de la autopista = the gas station on/along the highway (the one that belongs to that highway area)

Yes, but it changes the feel:

• la gasolinera de la autopista = identifies which gas station (the “highway one”)
• la gasolinera en la autopista = emphasizes its physical location (it’s on the highway)

Both are possible; de la autopista often sounds like a label/category.

Para + infinitive expresses purpose:

• para llenar el tanque = to fill the tank / in order to fill the tank

If the subject changes, Spanish usually switches to para que + subjunctive:

• Paramos ... para que ellos llenaran el tanque (so that they would fill the tank)

Both can mean “to fill,” but:

• llenar el tanque is the most neutral and common for putting fuel in.
• rellenar el tanque can sound like “to refill/top up,” and may feel slightly more “filling again,” though it’s still understandable.

For gas, llenar el tanque is the safest, most natural choice.

It can mean either depending on context:

• Literally: fill the tank (completely)
• Commonly in conversation: get gas / fill up

If you want to be explicit about “completely,” you can add:

• llenar el tanque por completo
• llenarlo hasta el tope (fill it to the brim)

Yes, nos detuvimos is very common and often slightly more formal/neutral:

• Paramos = we stopped (very common, conversational)
• Nos detuvimos = we stopped (also common; can feel a bit more “we came to a halt”)

Both are correct in Latin American Spanish.