Old engine oil as wood preserver

[David in Normandy]

After reading a recent thread on here about using old engine oil mixed with diesel and coal dust as a creosote replacement I decided to try painting an old oak post in the garden just using old engine oil.

I didn't have any coal to hand and diesel costs money. The old engine oil came fresh out of the lawn mower and I painted it on while still quite warm. It seems to have worked well. The post soaked all the oil up within around 24 hours to become touch dry. It has since darkened over the last few days almost becoming black but looks just like it has been creosoted. The oily smell has subsided too.

The post supports two large half moon hanging baskets and looks quite good with the makeshift *creosote*.

I don't know how good it will be at preserving the post but I bet it has annoyed the resident woodworm which were infesting it badly in one place.

[NT]

I've had mixed results with oil & paraffin, fine in some cases, no good in others. And oil alone soaks in much less. Oak shouldnt need preserving though.

NT

[David in Normandy]

I guess the purpose of the diesel or paraffin is to transport the oil deeper into the wood. Though in the case of this post it didn't seem necessary. Probably because it was well seasoned, and hot day, bone dry wood and rough sawn. Putting the oil on hot probably helped too. It sucked in the first coat very quickly, especially where there were lots of cracks and woodworm holes - I guess capillary action worked there. The second coat applied around half hour later took longer to soak in. I was surprised it became touch dry though by the following day - spouse touched the post and I expected her to get a black oily finger but no. If I try it on less absorbent wood I'll probably try mixing it with a little diesel or petrol first.

[NT]

yes

Your 24 hours versus with paraffin anything from a few minutes to an hour. So you may have much less penetration there.

NT

[PeterC]

Not sure that it'll stop woodworm. I had woodworm in a bench in a shed; splashed it over several years with old oil, a drop of paraffin, some oil+R11 (CFC) etc. and the little abstrads just kept on muching away!

[edmarson.read]

I have some old Creosote, for treating wooden fencing. It has become quite thick because most of the paraffin solvent has evaporated. I've been trying, unsuccessfully to mix in paraffin in an attempt to thin it. Please, can anyone advise me on how to add paraffin, or old engine oil, to old creosote?

[newshound]

I'd use a paint mixing paddle, in a cordless drill, at low speed. Carefully.

[Archibald Tarquin Blenkinsopp]

Used engine oil is a health hazard.

AB

[Roger Hayter]

So's the creosote. It's hard to imagine a preservative that wouldn't be. You can only discriminate to some extent between toxicity to fungi and toxicity to people.

[harry]

Some "creosote" (creocote) is water based. See if your brush washes out with water to find out. If so, you can thin it with water. It's not as good as the old stuff.

[Brian Gaff]

Yes you could end up covering the environment with gloopy gunge. Brian

[George Miles]

[Archibald Tarquin Blenkinsopp]

I don't dispute that.

Used engine oil would modify any known hazards associated with the creosote though and I would guess that no serious work has been conducted in respect to combinations of the two.

Used engine oil in itself is a variable, the dangers outside the obvious ones of course are the age, the temperature it was used at, engine condition and what additives the owner of the engine used.

Given the choice I would use old engine oil. There again I'm clapped aincient and discourage children from the garden.

A socially responsible person would indeed use paraffin I suppose, or if it's water based creosote follow harrys suggestion which is actually in keeping with the NG subject matter for once :-)

AB

[harry]

If the post is in a non-visible place, a plastic bucket/other container nailed/glued over the top is the best preserver of timber posts. They rot from the top and at ground level.

[Chris Green]

I have a few hundred round wooden posts supporting electric fencing around our smallholding. I don't think I have ever had one 'rot from the top'. When they fail it's *always* at or just below the surface of the ground where they tend to stay wet *and* there's air.

The portion deeper in the ground is usually still in one piece and can be extracted by screwing a large screw into it and pulling up with the tractor's 3-point linkage.

The 'above the ground' part of the post is always perfectly sound still.

These are standard treated round wooden posts.

[Andrew Mawson]

Large square fence posts here on the farm get a good soaking with real creosote, but over the years the tops do tend to have water sit on them even when cut at a steep angle. Now I install a simple cap folded from sheet lead which solves the problem.

Andrew

[Tim+]

+1. Just replacing my garden fence (which is about 25 years old) and whilst there?s a little rot at the top of some posts, it?s not structurally damaging. As you say, the problem is at ground level. I?m treating the bottoms of my new posts with creosote (the real stuff).

Tim

[Roger Hayter]

Possibly it depends on the local climate. Round here (mid-Wales) it tends to be on the damp side, and posts seem to rot from the top almost as much as at the base.

[S Viemeister]

It may not happen often, but it _does_ happen. We had gateposts supporting a standard metal farm gate, which looked sound, but rotted away on the inside, from the top down. I don't know what treatment, if any, they received, as they were there when we bought the place. Most rot does seem to happen at ground level, but not all.

[S Viemeister]

Same on the north coast of Scotland. More rot at the base, but the tops rot, too. Folk up here often put a little 'hat' or mini-roof on top of the post.