Vá lốp, thay dầu rồi siết chặt gương chiếu hậu.

A natural breakdown is:

• vá lốp = repair/patch the tire
• thay dầu = change the oil
• rồi = then / after that
• siết chặt = tighten firmly
• gương chiếu hậu = rearview mirror

So the whole sentence means something like:

Patch the tire, change the oil, then tighten the rearview mirror.

No subject is stated explicitly.

In Vietnamese, especially in:

• instructions
• to-do lists
• workshop notes
• commands

the subject is often omitted if it is obvious from context.

So this could mean:

• You should patch the tire...
• Please patch the tire...
• We patched the tire...
• Patch the tire...

The exact subject depends on the situation. In many cases, it feels like an instruction or checklist item.

Here, rồi means then / after that / and then, showing sequence.

So:

• thay dầu rồi siết chặt gương chiếu hậu
  = change the oil, then tighten the rearview mirror

This is different from the common use of rồi meaning already, as in:

• Tôi ăn rồi = I already ate / I’ve eaten already

So rồi can have different functions depending on position and context. In this sentence, it connects actions in order.

Yes, the commas separate actions in a series.

The sentence lists several tasks:

1. vá lốp
2. thay dầu
3. siết chặt gương chiếu hậu

This is very natural in Vietnamese for instructions, task lists, or service descriptions.

English would often do something similar:

• Patch the tire, change the oil, then tighten the rearview mirror.

So the commas help organize the sequence of actions.

No. vá lốp means patch the tire or repair the tire, usually when it has a puncture.

• vá = patch, mend, repair
• lốp = tire

If you wanted to say replace the tire, you would use a different verb, such as:

• thay lốp = replace the tire

So vá lốp and thay lốp are not the same.

thay dầu means change the oil — remove old oil and put in new oil.

đổ dầu usually means pour oil in or add oil/fuel, depending on context.

So in vehicle maintenance:

• thay dầu = change the oil
• đổ dầu = add oil / pour in oil

In this sentence, thay dầu clearly refers to an oil change.

siết chặt means tighten firmly or make tight/secure.

• siết = tighten
• chặt = tight / firm / secure

Together, siết chặt emphasizes that the thing should be tightened securely.

Vietnamese often uses this kind of verb + result/intensifying element combination.
So siết chặt sounds stronger and more complete than just siết.

gương chiếu hậu is the normal term for rearview mirror.

Literally:

• gương = mirror
• chiếu hậu = reflecting/showing what is behind

You do not need to translate it word-for-word in normal use; just learn it as the set phrase for rearview mirror.

Because Vietnamese basic word order is usually Verb + Object, much like English.

Examples from the sentence:

• vá lốp = patch + tire
• thay dầu = change + oil
• siết chặt gương chiếu hậu = tighten firmly + rearview mirror

So this word order is very normal and expected.

It could be interpreted in more than one way depending on context.

Without extra words, it may sound like:

• a command
• a reminder
• a work order
• a checklist
• a summary of tasks

For example:

• On a repair note: Patch the tire, change the oil, then tighten the rearview mirror.
• In a description of what was done: [We] patched the tire, changed the oil, then tightened the rearview mirror.

Vietnamese often leaves tense and subject to context, so the sentence itself does not force just one interpretation.

You could add a command marker or a person being addressed. For example:

• Hãy vá lốp, thay dầu rồi siết chặt gương chiếu hậu.
  = Patch the tire, change the oil, then tighten the rearview mirror.

• Vá lốp, thay dầu rồi siết chặt gương chiếu hậu nhé.
  = a softer, more conversational instruction

• Anh vá lốp, thay dầu rồi siết chặt gương chiếu hậu đi.
  = Please patch the tire, change the oil, then tighten the rearview mirror.

These additions make the sentence sound more clearly directive.

Yes, it can be omitted, but the nuance changes slightly.

• Vá lốp, thay dầu, siết chặt gương chiếu hậu.
  = a plain list of actions

• Vá lốp, thay dầu rồi siết chặt gương chiếu hậu.
  = a list with a clearer sense of sequence, especially then tighten...

So rồi helps show that the last action comes after the previous one.

Yes, it is natural, especially in contexts like:

• vehicle repair instructions
• service notes
• maintenance checklists
• spoken directions in a garage

It is concise and practical. Vietnamese often sounds very compact like this when listing tasks.