I get the impression of "kinda-sorta"
Linking the CMP's page on entry-level stock refinishing, they suggest that an oil finish alone is kinda marginal in its water resistance, but adding 1 or 2 coats of "Tung Oil Finish" over a well oiled stock will give it very good weather resistance;
http://www.odcmp.com/Services/Rifles...ng_article.htm