I've got a couple dozen Griswold's and pre-Griswold "Erie" pans. So far pure flaxseed oil has worked best, but I haven't tried grapeseed yet. Haven't needed to.
I have almost three complete sets of griswold skillets. One large logo with heat rings and another large logo smooth bottom set. Griddles, waffle irons, Dutch ovens, trivets... Man, I just look at it now and shake my head. what was I thinking?! Luckily I somewhat came to my senses before I sprang for a #2 and #13....
edited to add:
Lids are worth more than the skillets are...