edlithgow    on 24 February 2019

Don't know, but I'd think you could essentially stop it deteriorating by pre-oiling it.

Its likely deterioration will be by oxidation and possibly acid hydrolysis of the paper, assuming its kept dry.

Filling the filters with oil will largely exclude oxygen, and the buffering of the oil should neutralise any acid.

If you keep them in a sealed container the oil shouldn't oxidise much either.