Sonny wrote:
The simple answer would be . . . .. NO.


Agreed. About the only thing possibly reasonable to apply would be
(expensive) tung oil, plus the time to apply it. Might as well go buy
treated lumber, which is much more appropriate for that application
than anything you could apply, yourself, to those boards.

Tung oil (or anything similar) would be wasted for the application/purpose.

If OP is adamant of using this for the purpose, something otoo the
CopperCoat or CreoCoat treatments is at least of some value...

http://www.wolman.com/product_category_list.asp?CatId=82

Wolman is just one manufacturer; OP should check at whatever is his
favorite local retailer for what is at hand.

Another option: Since they are for no other purpose, than taking up
space, paint them, with an oil base primer & paint, and get some use
from them.

If this is good salvage material as it sounds as is, I'd personally
suggest taking them back to the Habitat (or similar) store and go buy
treated landscape timbers for the purpose. That way both somebody can
get useful service from the framing lumber and OP will have something
suitable for his purpose as well...

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