treating fence

I'd use a wire brush

NT

That FAQ is dodgy.. engine oil is not a good preservative.. it never has been and never will be.

OK but perhaps you would like to tell us why.

Steve

To start with its not water repellent after its weathered for a week or two. Its as dangerous a creosote. It usually looks awful.

Anyway a fence doesn't need any treatment to stop it rotting.. provided its thin enough to dry out. Just put a water based colour wash on it.. they last about 10+ years.. my feather edge fence is 27 years old and has had two washes on it. No brushed on stuff will stop the posts rotting.. especially if they are set in concrete.. just repair them with godfather posts when they rot off.

Why should it be? It's hydrophobic alright but thin enough to be displaced by water when the two are mixed. Petroleum waxes are a better bet for the posts

Years ago I had a pile of half inch softwood, so I used it to hold some earth up, even though it was much thinner than recommended. I used oil & paraffin, the wood was in contact with damp/wet soil 24/7, and shortly before I left years later I dug stuff out from by the woodwork, and found to my surprise zero sign of deterioration where it was against the soil. If I'd used the modern waterbased crp it would have rotted away long before.

engine oil remains stable inside car engines, so its hard to see how it would fail after 2 weeks. Unless perhaps one put very little on and it all soaked away from the surface. It does need to be slathered on thick for best result.

if it were it would share the same warning labels. Its used engine oil that has attracted controversy, not new stuff.

I've done oil and B&Q preservative side by side. After 2 days its impossible to see any difference. Only on the first day it looks any diffferent. Maybe youre thinking of used engine oil, which is dark.

I've got a fair bit of rotten thin wood where it wasnt treated, some a few mm thick, some quarter inch, some 1.25", and some 2". All well ventilated on both sides.

NT