SonexBuilders.net

As part of the recommended method of attaching the wings to the fuselage, Sonex recommend the application of WD 40 to the wing spar.

WD 40 is not particularly good lubricant - some would argue not a lubricant at all, rather being a water (W) dispersant (D) fluid.

So what is the actual purpose of the WD 40 application ?

Depending on your opining/advice above - what alternatives/better products would you recommend?

The WD-40 helps the spars slide past each other in the tight fit spar tunnel. It isn't necessary but does help. You don’t want something thick like oil or grease that’s going to stay and collect grime and dirt between the spars over time. I’m guessing that wd-40 was called out because it evaporates quickly, is cheap, won’t hurt aluminum, and is widely available. There are probably better products but WD-40 does the job and won’t get them tech callas asking what other less readily available products are or where to buy them. It’s just a temporary lubricant to get the spars to slide past each other. It serves no other purpose once assembled so use whatever you think is best.

My understanding is that WD40 is a penetrating oil.

Arjay wrote:My understanding is that WD40 is a penetrating oil.

Thanks Arjay,

WD stands for Water Dispersant - In addition to its original fluid, WD40 now has a large range of, mainly, lubricants under the WD40 brand.

Check with Wikipedia - but I think the original fluid may have been developed for military use. Other uses were then found eg penetrating oil

I used silicone spray on the spars themselves, and the ends of the tunnels where the mounting blocks are. It's a better lubricant than WD-40. I used Redline Assembly lube on the PINS that I used instead of bolts.

The WD-40 story is fascinating, this is the fullest version I've seen http://www.todayifoundout.com/index.php ... ted-wd-40/

FY! - Sonex tell me that the advice to use WD 40 on the wing spars, to aid wing attach is ancient history & will be removed (now that I have asked about it)- no lube is required on the spar, lithium grease (or similar) may aid the fitting of the spar pins.

karmarepair wrote:
The WD-40 story is fascinating, this is the fullest version I've seen http://www.todayifoundout.com/index.php ... ted-wd-40/

WD 40 history/present day - Interesting but somewhat lacking. Here in Australia WD 40 original, is available in liquid form (as well as aerosol) which I much prefer, usually purchasing in 5L container & decanting as needed into a squirt bottle. It may be my imagination however the liquid seems to be a more viscus product than the aerosol.

Further WD 40 had become a brand name for a whole range of materials eg WD 40 spray lithium grease, silicon's, gardening tool cleaner/lubricator, PTFE dry lub, etc etc.

In general I find most of the WD 40 spray products to be of inferior quality compared with many other products of similar/same name.