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Hot or Not? WD-40 For Rust Prevention

By Nick Carter

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We recently found something interesting at Brownells gunsmithing supply — they tested how well a number of substances prevented rust.  The results surprised us:  Plain old WD-40 was the most successful in keeping rust from forming on a mild steel surface, outperforming many other substances engineered specifically the job.

So what do you think, Hot or Not?  Let us know in comments.

Knowing the Limits of Rust Preventatives [Brownells]


This entry was posted on Tuesday, March 31st, 2009 at 11:53 am and is filed under Hot or Not. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

17 Responses to “Hot or Not? WD-40 For Rust Prevention”

  1. mark Says:
    March 31st, 2009 at 12:01 pm

    Doesn’t WD stand for water deterrent. Sounds like it’s doing what it’s designed for.

  2. Gordon Says:
    March 31st, 2009 at 12:13 pm

    I vaguely remember another study showing T-9 to be best. I’ll see if I can find the web site or reference.

  3. ToolGuyd Says:
    March 31st, 2009 at 12:41 pm

    WD-40 is excellent for water displacement. I never would have expected it to last as long as those experiments describe. I would have thought that the steel’s exposure to “scorching heat” and “horrific thunderstorms” would have cleaned most of the WD-40 off of the steel.

    Is anyone up to running a copycat test?

  4. Chuck Says:
    March 31st, 2009 at 12:42 pm

    Better than Cosmoline? The Russians had it wrong?

  5. bs Says:
    March 31st, 2009 at 12:42 pm

    YEA, some of that stuff is pretty expensive. I like to use wax on my table saw. its in the barn and during temperture changes a lot on humidity can condensate on it. Just plain old parafin or an old candle. clean the rust off first then apply wax. makes it sliperry too.

  6. Dave Says:
    March 31st, 2009 at 12:53 pm

    What, no test of Ed’s red?

    (google it- it’s a home-made freeing oil recipe)

    Dave

  7. Mike P. Says:
    March 31st, 2009 at 1:11 pm

    WD-40 did very well, but if you read the article, it was not “the most successful”.
    “Rig Universal Grease” was the best (”No evidence of rust formation or discoloration. The degreased plate shows the metal is unmarked.”) WD-40 results = “Minimal rust formation is present; almost no pitting is visible after degreasing.”

  8. Gordon Says:
    March 31st, 2009 at 1:18 pm

    The article I was thinking about was in Wood Magazine, March 2004, which compares 14 products for rust removal and prevention. T-9 won. http://www.woodstore.net/rustbusters.html

  9. Toolhearty Says:
    March 31st, 2009 at 1:31 pm

    Gordon: Link goes to $3 pay-per-download catalog page.

  10. Gordon Says:
    March 31st, 2009 at 3:18 pm

    Toolhearty: try this link http://www.boeshield.com/index.htm

  11. Ron Says:
    March 31st, 2009 at 5:53 pm

    WD-40 (water displacement formula #40) was developed by a fellow at General Dynamics in San Diego for the Atlas rocket, which had an all stainless steel structure at the time.

  12. diluded000 Says:
    March 31st, 2009 at 9:48 pm

    I wonder how paste wax would have fared in this test. I use it on my cast power tool surfaces several years ago, and they don’t have any rust. But I live in a really dry climate.

  13. Joe Says:
    April 1st, 2009 at 6:38 am

    Dave–thanks for the Ed’s Red tip–it looks like a good ‘un. Coincidentally, I’ve used ATF in the past and it’s worked well (it was “available”). And since WD40 is largely kerosene, that’s not a big surprise to see.

  14. Barry Says:
    April 1st, 2009 at 8:19 am

    I vote not…

    WD-40 displaces water for a short period, but dries out in a few days.

  15. Joel Says:
    April 1st, 2009 at 11:08 am

    @ Joe:

    I’ve always wondered about how ATF would fare in a trial like this. That stuff is damned sticky, and coats well, and doesn’t seem to wash easily.

    I’ve read that phosphorus can be a big help in rust prevention, and that the common formulations of chainsaw bar oil make an excellent rust repellent/inhibitor.

    I don’t know how either ATF or CBO would work on a gun…

  16. Bren R. Says:
    April 1st, 2009 at 11:25 am

    I use Ed’s Red as an immersion solvent for gun parts. It works very well, leaves a nice thin coat of ATF (which acts as a lubricant and rust preventer). The only problem is it stinks to high hell.

  17. shopmonger Says:
    April 1st, 2009 at 6:14 pm

    WD is great after you wash tools to “Displace water” then use another lubricant to “save them” if you are planing to store them for a long period of no use….

    other than that for cast iron waxing is the way i keep my tools in goods condition

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