O radiador e o fluido de freio podem vazar.

Because the subject is made of two things:

• o radiador = the radiator
• o fluido de freio = the brake fluid

When two singular nouns are joined by e (and), they normally make a plural subject, so the verb must also be plural:

• O radiador pode vazar. = The radiator can leak.
• O radiador e o fluido de freio podem vazar. = The radiator and the brake fluid can leak.

So podem is the plural form of poder in the present tense.

Podem vazar is:

• podem = can / may
• vazar = to leak

So together it means can leak or may leak.

In this kind of sentence, podem usually expresses possibility or something that is able to happen, not permission.

Because both nouns are being treated as separate, specific items:

• o radiador
• o fluido de freio

In Portuguese, it is very common to repeat the article with each noun in a list like this.

So:

• o radiador e o fluido de freio = the radiator and the brake fluid

If you left out the second o, the sentence would sound unnatural in normal Portuguese.

Because fluido de freio is a standard compound expression meaning brake fluid.

Here, de shows type/function, similar to how English uses one noun to modify another:

• car door
• brake fluid
• engine oil

Portuguese often uses de for this:

• fluido de freio = brake fluid
• óleo de motor = engine oil

If you said fluido do freio, it would sound more like the fluid of the brake, referring to a specific brake, which is not the normal way to say brake fluid.

Because in fluido de freio, freio is part of a fixed noun phrase naming the substance.

Portuguese often keeps the second noun singular in this kind of expression:

• escova de dente = toothbrush
• máquina de lavar = washing machine
• fluido de freio = brake fluid

Even though a car has multiple brakes, the standard term is still fluido de freio.

In this sentence, yes, vazar means to leak.

But vazar can have a few related meanings depending on context, such as:

• to leak (liquid/gas escaping)
• to let something leak out
• informally, sometimes to leave/get out of somewhere

Here the mechanical context makes the meaning clearly to leak.

Examples:

• O óleo está vazando. = The oil is leaking.
• O tanque vazou. = The tank leaked.

Grammatically, poder can express either:

• ability/possibility = can, may
• permission = can, may

But in this sentence, permission makes no sense. A radiator and brake fluid are not being allowed to leak. So the meaning is clearly possibility:

• can leak
• may leak

A rough Brazilian Portuguese pronunciation is:

O radiador e o fluido de freio podem vazar.

Approximate pronunciation: oo hah-dyah-DOR ee oo FLOO-ee-doo djee FRAY-oh POH-dein vah-ZAR

A few notes:

• r at the start of a word often sounds like an English h in Brazil:
  • radiador → starts roughly like hah-
• de before some sounds can sound like djee in many Brazilian accents
• freio sounds roughly like FRAY-o
• vazar has stress on the last syllable: va-ZAR

This is only an approximation, but it should help you hear the rhythm.

Yes, but it means something different.

• podem vazar = can/may leak
  (possibility, risk, something that might happen)
• estão vazando = are leaking
  (it is happening now)

So:

• O radiador e o fluido de freio podem vazar.
  = The radiator and the brake fluid can leak.

• O radiador e o fluido de freio estão vazando.
  = The radiator and the brake fluid are leaking.

Fluido de freio is completely natural and correct in Brazilian Portuguese, especially in technical or automotive contexts.

You may also hear:

• líquido de freio

Both are used. Fluido de freio sounds a bit more technical, while líquido de freio is also very common in everyday speech.

Most literally, o radiador e o fluido de freio means the radiator and the brake fluid, so it sounds like it is referring to specific parts, probably in a particular vehicle.

However, Portuguese often uses the definite article in ways that sound broader than English. Depending on context, it could also be understood as a general warning about those parts of a vehicle.

So the exact interpretation depends on context, but grammatically the sentence is framed as the radiator and the brake fluid.

It is an infinitive.

The pattern is:

• poder + infinitive

So:

• podem vazar = can leak

This is very common in Portuguese:

• podem quebrar = can break
• podem falhar = can fail
• podem aquecer = can heat up / overheat

So if you know poder + infinitive, you can build many similar sentences.