You can get spray on preserving grease from engineering supply companies and most bearing suppliers .
What IS IMPORTANT is to leave the barrel sitting on some newspaper or cardboard in the sunlight so it gets too hot to handle comfortably .
Without touching it with bare hands coat with the grease.
The old chin boiling grease works rally well too . Linklife .
melt the grease & pour over the hot barrel then allow to cool.
Once cool wrap tightly with glad wrap or pallet wrap .