Eu uso não só sabão, mas também detergente para lavar a panela.

It is a very common Portuguese pattern meaning not only ... but also.

In this sentence, it links two parallel items:

• não só sabão
• mas também detergente

So the structure is:

• não só + item 1, mas também + item 2

A good rule is: try to keep the two parts grammatically parallel. Here, both are nouns.

You can also use this pattern with other things, such as verbs or adjectives.

Yes, you can usually leave it out.

Portuguese often drops subject pronouns because the verb ending already shows who the subject is.
Here, uso already means I use, so:

• Eu uso não só sabão...
• Uso não só sabão...

Both are natural.

Including eu can add:

• emphasis
• contrast
• clarity

For example, Eu uso... might sound a bit more like I use..., especially if you are contrasting yourself with someone else.

Because they are being used in a general, substance-like sense.

In this sentence, sabão and detergente mean something like soap and detergent in general, not a specific soap or a specific detergent. Portuguese often leaves out the article in that kind of case, especially after verbs like usar.

Compare:

• Eu uso sabão. = I use soap.
• Eu uso o detergente que você comprou. = I use the detergent you bought.

So here, no article sounds natural.

In everyday Brazilian Portuguese:

• sabão usually means soap, often bar soap or laundry soap
• detergente usually means dish detergent, especially the liquid product used for washing dishes

So the sentence contrasts two cleaning products.

Depending on context, sabão can be broader, but in Brazil detergente is the usual word for the liquid dishwashing product.

Because after para to express purpose, Portuguese normally uses the infinitive.

So:

• para lavar a panela = to wash the pan / for washing the pan

This is the same idea as:

• Comprei uma escova para limpar o chão.
• Usei água quente para cozinhar.

In informal spoken Brazilian Portuguese, para often becomes pra:

• pra lavar a panela

That is very common in speech.

A panela means the pan, while uma panela means a pan.

Using a panela suggests:

• a specific pan already understood from context, or
• the pan being talked about in that situation

Using uma panela would sound more like introducing it as an unspecified object.

So:

• lavar a panela = wash the pan
• lavar uma panela = wash a pan

It is very standard and recommended here.

With não só ..., mas também ..., a comma is commonly used, especially in careful writing, because it clearly separates the two halves of the structure.

So this is a good model:

• Eu uso não só sabão, mas também detergente...

You may sometimes see no comma in shorter or more informal writing, but using the comma is a safe choice.

In this fixed pattern, the most natural place is exactly where it is:

• não só X, mas também Y

So:

• não só sabão, mas também detergente

That is the normal structure.

Portuguese does allow também in other positions in other sentence patterns, but if you want the clear not only ..., but also ... structure, this placement is best.

For example, this is a different structure, not the same one:

• Eu não uso só sabão; uso detergente também.

That can work, but it does not feel exactly the same as the original sentence.

Their genders are:

• o sabão
• o detergente
• a panela

So sabão and detergente are masculine, and panela is feminine.

In the sentence, you only see the article with panela:

• a panela

The other two nouns appear without articles, but their gender is still masculine if you need to use an article elsewhere.

Usually, uso in the simple present means I use in a general or habitual sense.

So this sentence most naturally sounds like:

• something you generally do
• a usual method
• a regular habit

If you want to emphasize right now, Brazilian Portuguese often prefers:

• Estou usando não só sabão, mas também detergente...

So:

• uso = I use / I usually use
• estou usando = I am using

Yes, lavar a panela is completely natural.

It specifically focuses on the pan.

If you want to talk about washing dishes in general, Brazilians very often say:

• lavar a louça = wash the dishes

So the difference is:

• lavar a panela = wash the pan
• lavar a louça = do the dishes / wash the dishes

The original sentence is natural because it is talking about a specific item.

Because here não is part of the expression não só ... mas também, not simple verb negation.

So:

• não só = not only

It is modifying the comparison between sabão and detergente, not making the sentence negative.

If you said:

• Eu não uso só sabão...

that could sound more like I don't use only soap..., which is close in meaning, but structurally a bit different. The original version is the cleaner textbook-style pattern.

So the sentence is not saying I do not use.
It is saying I use not only X, but also Y.