For reasons, I'm going to put a D lock through the wall of my flat, and I want to protect it against sealing up with rust.

There are coincidentally a pair of perfect holes already in the wall (from old plumbing, I assume?) that I can poke the legs of the D-lock through and then lock from the other side of the wall.

The lock is my current Bike lock, which is used almost daily, is fairly old, and for which the 'teeth' (where the D enters the locking bar) are fairly rusty.

Every 6 months or so, the teeth (and the holes that the go into on the locking bar) get sufficiently rusty that it starts to be a moderate struggle to open the lock if I haven't used the bike for a day or two. At that point I clean it throughly with WD-40 and kitchen towel, to get as much of the rust off as possible and just continue.

This has worked perfectly well for the past 2 years.

Now I want to put the lock through the wall, lock it and leave it in place for years, ideally without ever touching it/having to regularly clean it. The Teeth and locking bar will be on the inside of the wall, the outside point is sheltered and I'll try to block up around the hole to keep rain for passing through, so there won't be any substantial water getting to it ... just general atmospheric humidity (London, UK)

Obviously I'm going to do a heavy-duty clean with WD-40, but I'm wondering whether I should be doing anything more than that to try to protect it?

Some sort of heavier oil, or similar?

Do I need to? What should I be doing? What products/product names should I be looking for? Is there anything I should know about the technique of applying these things?

  • 6
    WD40 is not a long term rust proofing solution. Bicycle chain oil will do a better job. Jun 14 '16 at 10:49
  • 3
    I'm voting to close this question as off-topic because it really has next to nothing to do with home improvement.
    – Michael Karas
    Jun 14 '16 at 11:38
  • 1
    Agreed, though a more general question about metal and weather might be reasonable. (Personally, this sounds like time to replace an unreasonably cheap "toy" lock with something made of appropriate materials for the environment.)
    – keshlam
    Jun 14 '16 at 12:37
  • 4
    Don't get anywhere near a lock with WD-40, nor any types of oils that could leave a grime capturing film behind. You could possibly wipe the outside of the lock down with oil, but be very careful not to get any inside the lock mechanism. The only things you should put into a lock, are a key, and PTFE lock lubricant.
    – Tester101
    Jun 14 '16 at 13:21
  • 3
    I also use powered graphite in my locks
    – Ed Beal
    Jun 14 '16 at 19:04

It sounds like you're not talking about the actual key lock itself or the pins & tumblers, and I think you only mean the steel D bar & latch, very similar to car door hinges & latches, so a similar solution should work.

The owner's manuals for cars I've had recommended using one of these two, re-applied every few months or whenever it seems harder to open:

  • Grease - white lithium grease (often used on car door hinges & latches), or even any grease, wheel bearing/axle grease, even cooking grease for a short while, just about any type that won't wash away easily.

  • Oil - plain motor oil, or a 3-in-1 type

You could probably still use regular WD-40, it is very good at preventing rust, but it does go dry & a little sticky pretty quickly, so you'd have to re-apply it much more often, maybe every month or so.

Or, you could use a specialty corrosion inhibitor spray like:

  • WD-40 Specialist Long Term Corrosion Inhibitor Spray - The company website advertises a comparison against some other methods with this image enter image description here
    but Amazon might have some less biased reviews.

Or a firearms product like Birchwood Casey RIG Universal gun Grease that has reviews like "I have used this product since 1951... and never had any problems with rust."

I've also read that petroleum jelly or anything wax-like, even beeswax can be effective too. Probably anything that coats the metal and keeps water & air away should work, it just depends on what you've got handy & how often you want to re-apply it.

  • yes, you're exactly right about what I'm talking about. Many thanks!
    – Brondahl
    May 11 '17 at 7:05
  • @Brondahl You're welcome, but it's even better to upvote good answers and select as correct the best answer (the up arrow / "This answer is useful" button & check-mark on the left). Thanks
    – Xen2050
    May 18 '17 at 11:52

I use a spray on waxy film protectant for motor shafts after rebuilding them (so they don't rust while waiting to be used). There are other long term corrosion inhibitors that have tons more VOC's in them but this one works well on untreated steel to prevent rust.

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