Learn Hardcore Indonesian: Saya menyimpan minyak rambut di kamar mandi.

menaruh / meletakkan – to put/place something somewhere (more about the action of placing, not about long‑term storage).
menyimpan – to keep/store something as its usual or safe place, or to save something (money, files, secrets).

So if you say:

Saya menyimpan minyak rambut di kamar mandi.
→ The bathroom is where I normally keep it.

while:

Saya menaruh minyak rambut di kamar mandi.
→ I put it in the bathroom (focus on the act of placing it there; maybe just now).

Why is it minyak rambut and not minyak untuk rambut for “hair oil”?

Both exist, but they’re used slightly differently.

minyak rambut
Literally “hair oil,” but in Indonesian it’s a fixed collocation meaning a grooming product (hair oil/hair tonic/hair pomade). It sounds natural and is what people usually say.
minyak untuk rambut
Literally “oil for hair.” This is more general and descriptive: some oil (coconut, argan, etc.) whose function is for hair. You’d use this in explanations, ads, or when clarifying purpose.

In everyday speech, for a common hair product you keep in the bathroom, minyak rambut is the default and sounds more idiomatic.

Why is the word order minyak rambut (“oil hair”) and not rambut minyak?

In Indonesian, when two nouns are put together, the first noun is the main thing, and the second noun describes or specifies it.

Pattern:
Noun 1 (head) + Noun 2 (modifier)

So:

minyak rambut = oil (for) hair → “hair oil”
kamar mandi = room (for) bathing → “bathroom”
tiket pesawat = ticket (for) plane → “plane ticket”

If you said rambut minyak, that would literally be “hair (that is) oily/greasy,” not the product. So:

minyak rambut → the product (hair oil)
rambut berminyak → oily/greasy hair

Do I need a measure word or classifier before minyak rambut, like “a bottle of hair oil”?

Not necessarily. Indonesian often omits measure words when you speak generally.

Saya menyimpan minyak rambut di kamar mandi.
→ I keep hair oil in the bathroom. (General statement.)

If you want to be specific about quantity or container, you add a classifier:

sebotol minyak rambut – a bottle of hair oil
dua botol minyak rambut – two bottles of hair oil
sedikit minyak rambut – a bit of hair oil

Example:

Saya menyimpan sebotol minyak rambut di kamar mandi.
→ I keep a bottle of hair oil in the bathroom.

How do I say “my hair oil” in this sentence?

Several natural options:

minyak rambut saya – very common, neutral
- Saya menyimpan minyak rambut saya di kamar mandi.
minyak rambutku – informal, with -ku attached
- Aku menyimpan minyak rambutku di kamar mandi.
minyak rambut di kamar mandi itu punyaku – “that hair oil in the bathroom is mine” (different structure, but shows possession).

The most straightforward and neutral is:

Saya menyimpan minyak rambut saya di kamar mandi.

What’s the difference between di kamar mandi and di dalam kamar mandi?

Both are correct, but there’s a nuance:

di kamar mandi
→ “in/at the bathroom” (neutral, most common; already implies inside the bathroom space).
di dalam kamar mandi
→ literally “inside the bathroom,” a bit more explicit and slightly more formal or emphatic about the inside.

In everyday speech, di kamar mandi is perfectly natural and usually preferred. You’d choose di dalam kamar mandi if you specifically want to emphasize “inside” vs just “at the bathroom area.”

Why is it di and not ke in this sentence?

Di marks a location (where something is).
Ke marks a direction/destination (where something is going).

di kamar mandi = in/at the bathroom (location)
ke kamar mandi = to the bathroom (movement toward)

Menyimpan describes a state / where you keep something, not movement, so you use di:

Saya menyimpan minyak rambut di kamar mandi.
→ I keep hair oil in the bathroom.

If you were describing movement, you’d use another verb + ke:

Saya membawa minyak rambut ke kamar mandi.
→ I take/bring hair oil to the bathroom.

There’s no tense marker. How do I know if this means “I keep,” “I kept,” or “I will keep”?

Indonesian verbs usually don’t change form for tense. The basic sentence:

Saya menyimpan minyak rambut di kamar mandi.

can mean:

I keep hair oil in the bathroom. (habitual/general fact)
I kept hair oil in the bathroom. (if context is past)
I will keep hair oil in the bathroom. (in some future-planning contexts)

You rely on context or add time words:

Dulu saya menyimpan minyak rambut di kamar mandi.
→ I used to keep / I kept hair oil in the bathroom.
Nanti saya akan menyimpan minyak rambut di kamar mandi.
→ Later I will keep/store hair oil in the bathroom.
Sekarang saya menyimpan minyak rambut di kamar mandi.
→ Now I keep hair oil in the bathroom.

Can I drop Saya and just say Menyimpan minyak rambut di kamar mandi?

In normal Indonesian, you do need a subject here. Just saying:

Menyimpan minyak rambut di kamar mandi.

sounds incomplete or like a sentence fragment (e.g., part of instructions). It might be understood as “(You should) keep hair oil in the bathroom,” but it’s not a full sentence in neutral conversation.

Natural full sentences:

Saya menyimpan minyak rambut di kamar mandi.
Aku menyimpan minyak rambut di kamar mandi.

You can drop saya/aku if the subject is very clear and repeated in context, but Indonesian still tends to keep the subject more often than not.

What’s the difference between Saya and Aku here?

Both mean I, but they differ in formality and social context:

Saya – neutral and polite; used in most formal or semi-formal situations, or when you don’t know someone well.
Aku – informal/intimate; used with close friends, family, or in casual speech (especially among younger people).

So:

Saya menyimpan minyak rambut di kamar mandi.
→ Polite/neutral; safe in any context.
Aku menyimpan minyak rambut di kamar mandi.
→ Casual/close; sounds friendly with peers or family.

Grammatically, both are correct; it’s mainly a style and politeness choice.

Could I also say Aku menaruh / meletakkan minyak rambut di kamar mandi? How is that different from menyimpan?

Yes, you can, but the nuance changes:

menyimpan – to keep/store (emphasis on long-term place/safe-keeping).
menaruh – to put/place something somewhere (more neutral, everyday).
meletakkan – to put/place something (a bit more formal or careful-sounding than menaruh).

Examples:

Aku menyimpan minyak rambut di kamar mandi.
→ I keep hair oil in the bathroom (that’s its usual location).
Aku menaruh minyak rambut di kamar mandi.
→ I put the hair oil in the bathroom (focus on the action of putting it there).
Aku meletakkan minyak rambut di kamar mandi.
→ I place/put the hair oil in the bathroom (slightly more formal/careful).

In your original sentence, menyimpan nicely expresses a habitual storage place.

Can I move di kamar mandi to the beginning or somewhere else, like in English?

Yes, Indonesian word order is fairly flexible as long as you keep it clear. These are all acceptable:

Saya menyimpan minyak rambut di kamar mandi.
Saya menyimpan di kamar mandi minyak rambut. (grammatical but less natural)
Di kamar mandi, saya menyimpan minyak rambut. (emphasis on the location)

The most natural and common version is the original:

Saya menyimpan minyak rambut di kamar mandi.

Putting di kamar mandi right after the object is standard and sounds smooth. Sentence-initial Di kamar mandi, ... is fine for emphasis or style (e.g., in writing or storytelling).

Does kamar mandi always mean “bathroom”? Is it exactly the same as English?

Kamar mandi literally means “bath room” and usually corresponds to bathroom in English, but cultural usage can vary a bit:

In many Indonesian homes, kamar mandi is a room with a shower or bucket for bathing, often with a toilet in the same room.
Sometimes toilets are separate; then people might say toilet, WC, or kakus for the toilet, and kamar mandi for the bathing room.

In most everyday contexts, kamar mandi is the natural way to say bathroom (the room where you wash and often where the toilet is). In your sentence, it fits perfectly for “bathroom.”