O lubrificante protege a corrente.

In normal Portuguese, you usually need articles with nouns in a full sentence.

• o lubrificante = the lubricant
• a corrente = the chain

So O lubrificante protege a corrente sounds like a normal, complete sentence.

Leaving the articles out can sound unnatural in standard Portuguese, unless you are using a very abbreviated style such as labels, headlines, or technical notes.

Because Portuguese nouns have grammatical gender.

• lubrificante is masculine, so it takes o
• corrente is feminine, so it takes a

This is something you usually have to learn with each noun. The ending does not always make the gender obvious. For example, even though lubrificante ends in -e, it is masculine here.

Here, it is a noun: lubricant.

But lubrificante can also function as an adjective in other contexts, meaning lubricating.

For example:

• óleo lubrificante = lubricating oil

In your sentence, though, o lubrificante clearly means the lubricant, so it is being used as a noun.

Protege is the 3rd person singular present form of the verb proteger (to protect).

The subject is o lubrificante, which is singular, so the verb must also be singular:

• eu protejo = I protect
• tu proteges = you protect
• ele/ela protege = he/she/it protects

So:

• O lubrificante protege... = The lubricant protects...

Portuguese often does not use subject pronouns when they are not needed, because the verb form usually makes the subject clear.

English says:

• It protects the chain

Portuguese normally says:

• Protege a corrente

Or, if you name the subject:

• O lubrificante protege a corrente

You could say ele protege a corrente, but that would usually only be used when you want to emphasize it or contrast it with something else.

Here, corrente means chain, especially a mechanical chain, such as a bicycle chain.

This word can also mean other things depending on context, such as:

• current (electric current)
• stream or flow
• trend in some expressions

But in a sentence about lubricant, the natural meaning is chain.

In Portuguese, corrente is the usual word for a metal chain, especially in mechanical contexts like bikes or machines.

Cadeia can also mean chain, but it is used in different contexts, for example:

• a necklace chain
• a chain of events
• a business chain
• and very commonly, prison

So for a bike or machine chain, corrente is the normal choice.

In European Portuguese, protege is pronounced roughly like:

pro-TEJ(uh)

A few useful details:

• the g before e sounds like zh in measure
• the stress is on -te-
• the final -e in European Portuguese is often very reduced, almost like a soft uh or sometimes barely heard

So it is not pronounced like English pro-teej.

A rough pronunciation is:

kuh-REN-t(uh)

A few key points:

• the rr is a strong guttural r in European Portuguese
• the stress is on -ren-
• the en is nasal
• the final e is reduced, as often happens in European Portuguese

So the word will not sound exactly like it is spelled to an English speaker.

This sentence uses the most neutral and common word order:

Subject + Verb + Object

• O lubrificante = subject
• protege = verb
• a corrente = object

That is the standard order for a simple statement. Portuguese can change word order for emphasis, but this version is the most natural in ordinary usage.

It can be understood either way, depending on context.

It may mean:

• The lubricant protects the chain in a specific situation
• or a more general statement, like Lubricant protects the chain

Portuguese often uses the definite article where English might be more flexible. So O lubrificante protege a corrente can still sound natural even when talking about something in a general, practical sense.

The plural would be:

Os lubrificantes protegem as correntes.

Changes:

• o → os
• lubrificante → lubrificantes
• protege → protegem
• a → as
• corrente → correntes

So:

• O lubrificante protege a corrente. = The lubricant protects the chain.
• Os lubrificantes protegem as correntes. = The lubricants protect the chains.

Yes. They are cognates, so they come from the same origin and have very similar meanings.

• Portuguese: proteger
• English: to protect

That makes this verb relatively easy for an English speaker to recognize. Just be careful with pronunciation and verb endings, because they work differently in Portuguese.