i use a drop of WD-40 on carabiner gates; i first take the carabiner off the sling/dogbone; drop on; and then wipe thoroughly with toilet paper to clean any excess. that way nothing ends up on the sling.
but here's the gold standard:
http://blog.weighmyrack.com/when-how-an ... arabiners/
and some more useful info; none of which i can verify so use at own risk!
"According to this caving booklet:
http://www.draftlight.net/lifeonaline/ dyneema is not damaged by lubricants such as WD40 (see page 18 of the download). Some people actually recommend spraying WD40 on slings to stop them freezing in winter!"
http://www.ukclimbing.com/forums/t.php?t=177906
"I also conducted a series of tests on Nylon runners with WD40. This was undocumented since it was my own gear. Again, these were still full strength. I don't remember the data off hand since I did this 4 years ago. I don't think that WD40 affects Spectra (our runners are half Spectra and half Nylon). However, I have not tested this out and verified it conclusively. Chris Harmston (
chrish@bdel.com)."
http://www.rockclimbing.com/forum/Climb ... _P2200922/