Davines OI Oil

The one product in the range that does almost everything, and the reason OI has the following it does.

It detangles, smooths, hydrates and adds shine, on wet hair or dry. Most oils pick one of those and lean into it. This does the lot, which is why it ends up being the bottle people replace rather than the one that sits unused.

What you'll notice

Softness first — properly soft, not coated. Hair combs through without dragging, frizz settles, and the shine looks like healthy hair rather than product sitting on top. The OI scent is in this too, and it lingers.

Who it's for

Most hair types, which is unusual for an oil. Dry or frizzy hair gets the most from it, but fine hair can use it as long as you're sensible with how much.

Which size, and worth saying about the price

It's the most expensive thing in the range, and the honest answer is that a bottle lasts a long time. Two or three drops does mid-lengths and ends on most heads. If you're using enough to notice it running out quickly, you're using too much.

On value: the 135ml works out at roughly half the price per ml of the 50ml. If you already know you like it, the bigger bottle is the sensible buy. The 50ml is for trying it first, or for travelling.

How to use it

A few drops in your palms, rub them together, work through mid-lengths and ends. On damp hair before drying for smoothness and heat protection, or on dry hair to finish and control frizz. Start with less than you think — you can always add.