In 1921, the perfumer Ernest Beaux gave Gabrielle Chanel a set of samples to choose from, and she picked the fifth. N°5 was built around a generous dose of aldehydes, which gave it an abstract, clean sparkle, and it is still one of the best-known perfumes in the world. Marilyn Monroe famously said the only thing she wore to bed was a few drops of it. Chanel now makes N°5 The Body Oil, which is in the second grid, and it is my favorite way to wear a scent that can feel like a lot sprayed from a bottle.

That is the side of body oil people forget. Some oils are really about skin: firming, softening, fading the look of stretch marks. Others are a gentler way to wear perfume, closer to the skin than a spray.

The first grid is skin oils, from simple dry oils to the firming ones. The second is body oils from perfume houses, from N°5 to Baccarat Rouge 540.

The one rule for both: put it on while you are still damp from the shower. The oil spreads further, you need much less and it seals in the water on your skin instead of sitting on top.

Here is a test I like: three pumps on damp skin, then pat dry gently with a towel. If you still feel greasy after five minutes, use two next time.

If you want an oil that simply sinks in and leaves skin soft, start with Moroccanoil's Dry Body Oil. It is a true dry oil, fast-absorbing, with argan, olive and avocado oils, so you can get dressed without waiting long.

Most of the others promise some firming, and the difference is in the scent and the extras. Clarins' Tonic oil is made with pure plant extracts, hazelnut oil, rosemary, geranium and mint, to firm, tone and soften the look of stretch marks, and it smells herbal and fresh. L'Occitane's almond oil is 50 percent almond oil and does a similar job with a soft almond scent. Omorovicza's Firming Body Oil is fragrant with sage, chamomile, rosemary, rose and geranium, with vitamin E for elasticity.

OSEA's Undaria Algae oil is seaweed-infused, rich but never greasy, with an aromatherapy scent. Nécessaire's Grapefruit oil is a treatment oil with capsaicin, five peptides and five ceramides to tone and firm and reduce the look of cellulite, and it is dermatologist-tested. Sol de Janeiro's Bum Bum Firmeza uses guaraná caffeine and microalgae for a firmer, less puffy look.

Augustinus Bader's The Body Oil is the one I would give as a gift: lightweight and fast-absorbing, with the brand's TFC8 complex, made to hydrate, soothe and smooth the look of cellulite and stretch marks.

Whatever you choose, press it into damp skin straight out of the shower, where it spreads further and leaves a soft glow instead of a slick. Here is a pairing I like: a firming oil in the morning, when you can massage it in, and something plain at night.

What I would skip: body oil right before pulling on silk or pale clothes. Give it a few minutes first.

A scented body oil is the quietest way to wear a perfume. It sits closer to the skin than a spray, so people notice it when they are near you, not across the room.

Chanel makes two. N°5 The Body Oil is inspired by the rose and jasmine at the heart of N°5, made with 84 percent naturally derived ingredients, in a glass bottle shaped like the perfume's. Coco Mademoiselle's body oil is a spray, with jojoba and meadowfoam oils, and it absorbs quickly without feeling greasy.

Maison Francis Kurkdjian's Baccarat Rouge 540 oil carries the same jasmine, saffron, cedar and ambergris as the perfume, with a light texture that sinks in fast. Byredo's Gypsy Water is a lightweight dry oil, and the brand says the oil base makes the scent last longer on skin. Creed's Silver Mountain Water perfumed oil is the fresh one, bergamot and blackcurrant over tea, sandalwood and musk.

For evenings and summer, two shimmer oils. Tom Ford's Soleil Blanc leaves a sunkissed sheen and smells of bergamot, cardamom, pistachio and ylang ylang. Victoria Beckham's Portofino '97 is a golden shimmer oil with bergamot, amber and vetiver, lovely on collarbones and shoulders.

And Diptyque's Relaxing Oil in Oil comes from its Les Rituels de Soin collection, inspired by ancient bathing traditions, the one for a slow night in.

Here is the layering trick I like: the body oil on damp skin, then one spray of the matching perfume on top. The scent tends to last longer layered this way.

What I would skip: shimmer oil under a white shirt. Save it for bare shoulders.

I think body oil is the easiest luxury in a bathroom, and the one most often wasted, because it ends up in a drawer and gets used twice a year.

Keep it next to the towel, where you will see it the moment you step out of the shower. Choose a skin oil for every day and a scented one for the nights you want to smell like something. Put it on damp skin, use less than you think and give it a minute before you get dressed. That is the whole routine.