Sylvia,
 
Sorry, I guess I was one of the ones who "shot you down."  I personally
went from vegetable oil (terrible thing to use but 35 years ago my only
shell book just said "oil"), mineral oil (bit of a pain in the neck, but
okay), to WD-40 (easy to use with spray can and all), to silicone.  I
have two small (35-40mm) unidentified murex shells (no location data,
from a rock shop in Tucson) that I treated with oil.  The problem is that
I do not specifically remember using WD-40 but it was during the time I
was routinely using it on my shells.  In any case, both white shells are
now yellow.  Taking no chances, I switched to silicone (saw an article
about its use by Clover and figured if it was good enough for him it was
fine by me) and I have been happy with it.  During the same period I
found some of my guns (which just sit in a closet all year in cases) had
developed a thin, shellac type of coating in the trigger mechanism.
Again, the suspected culprit was WD-40 - although I also used other oils.
 
I am glad you are having no problems with WD-40 as it is easier to obtain
than silicone (must be the color of the can, since both are readily
available).  I will probably stick with silicone but I may try WD-40 on a
few shells as a long term experiment.  I am still suspicious of the
product but willing to change if I am both led to water and then beaten
over the head repeatedly until I drink.
 
The nice point here is once again Conch-L shows its value as an open
forum.
 
Tom Eichhorst (a bit confused about oil in New Mexico)