98 year old local has been using butter or lard all her life...and Mother Earth New did tests some years back...I dont keep mineral oil in the house but I always have butter or lard
My grandfather smoked cigars till he was 101, then quit...kinda sad, he died soon after
Is your 98 year old local claiming her longevity is due to using butter or lard, otherwise I don't see a correlation.
Mother Earth News reports not washing, using nothing but refrigeration is best,
Click Here for the full report you mention.
They did not test Mineral oil...to bad.
Below are a few sources and interesting reads just to start.
You of course must decide what method works best for you.
Hope this helps:
http://www.preparednesspro.com/safely-preserving-eggs
http://prepared-housewives.com/preserving-eggs-experiment-1-year-later/
http://www.offthegridnews.com/off-grid-foods/preserving-eggs-for-the-long-term/
http://lifehacker.com/5923565/coat-eggs-in-mineral-oil-to-keep-them-fresh-longer
http://everydaylife.globalpost.com/long-eggs-last-covered-mineral-oil-42798.html
... Shes saying shes 98 and hasnt died yet from using butter.
And Im not about to take my super healthy home farmed eggs and soak them in distilled petroleum.