UKH

Crampons came out the attic earlier and I noticed a thin dusting of rust on some of the points where the coating (black oxide??) had worn off. I allow them to dry fully before storing them and have them a scrub with WD40 last year.

How do you guys look after your crampons (and other metal gear I guess)

The surface oxidation will be inconsequential. It will brush off with your finger tips. 

To care for crampons, just dry them out and store them dry. Unless you have been doing something funky with them like climbing chalk sea cliffs. In which case wash the salty sea grease off first.

The black coating is usually a polymeric powder coat, paint.

WD 40 does have quite a high water content. A rub down with an oily rag or just drying naturally is probably best. 

Seriously, you kick them into rock half the time and tromp around over rocks in them the rest of the time! Wipe them off so they don't make anything else in your rucksack grubby and don't worry about it again!

Actually, there is no water in the WD-40 formula. The letters means Water Displacement and it was the 40th formula in the pursuit to develop an anti corrosion agent for the fuel tanks of some intercontinental ballistic missiles. I read the story on wikipedia:
https://en.wikipedia.org/wiki/WD-40

And at the same time Wikipedia appears to remain silent about GT85 - which presumably took over twice as long to develop. And which I'm still not clear about in terms of how it differs from WD40

It smells slight different (tongue in cheek)

I dry, sharpen and oil them with balisto (biodegradable) at the end of the season. 

I find that any surface rust does not survive contact with the snow and ice.  So just putting them away clean and dry should be enough.  If they have any plastic parts I'd advise storage where they won't be subject to large or sudden changes in temperature/humidity as with any equipment you want to have a long life.

I think it contains PTFE (Teflon effectively), unlike WD40

WD40 contains quite a nice perfume, it's descended from Shalimar by Guerlain believe it or not. 

(That's industry inside information for you.)

Thanks, I have been mislead. It is a fairly common myth I have heard from a variety of sources. 

I've just sharpened mine for the first time. You could barbecue sausages on those front points.

That teflon spray is good on the ant baling plates and spacer bar as it helps to shed the snow from the plates if you don't have the grivel bubble type. Doesn't last long, but easy to reapply.

Wd40 does not contain water. WD is even short  for water displacement! I often use it as a finishing coat on ice screws, but have done on crampons too, it’s great for that!