What wood oil?

As it is down below and out of the weather, I'd think strongly along the lines of white shellac. This is much paler than normal common-or-garden shellac. Unfortunately you won't be able to use this in any places that get rough treatment, like a table-top, but for locker doors, roof beams and the like, it should be fine. You may find it harder to get than normal shellac, but a decent cabinetmaker should be able to tell you where to find an industrial supplier Your Yellow Pages phone directory may also be useful.
Peter.
 
Top