Seal Post Tops with Linseed Oil Mixture

What happens here

To seal the exposed tops of the cut pressure-treated posts, the presenter prepares a 50/50 mixture of boiled linseed oil and mineral spirits (paint thinner). He creates a makeshift paint bucket by cutting the top off a recycled windshield washer fluid jug. He pours the boiled linseed oil into the new container, then adds mineral spirits, mixing thoroughly with a paint brush. He then applies this mixture generously to the exposed cut surface of the post tops, allowing it to soak in. He emphasizes that this treatment protects the wood, preventing rot, and will evaporate naturally.

Goal: Protect exposed post tops from rot