[Carl Erickson Jr]

The US Army used to issue a small container of grease to go in the stock of the M1 rifle. The grease was selected after testing shown it to be the best all weather grease. The grease is white lithium Lubriplate available at any Auto Parts store.
As for a general lubricant, cleaner and preservative oil I use GI CLP (cleaner lubricant preservative) or equivalent. Seems to work well for me in many different applications.