In addition to their lubricant properties oil and grease are often used to pack or coat metal parts to prevent corrosion. How long will this protection last? How long will grease or oil last in containers?
It’s SOP for a lot of cookware (e.g. cast iron skillets) so I would think months anyway.
Forever, until something penetrates the oil, or the oil becomes something else that’s subsequently removed.
Depending on the oil or grease, container, environment, etc., there’s a possibility of chemical changes such as oxidation.
I’ll qualify “forever” as not applying beyond the heat death of our solar system.
If the grease or oil is undisturbed, and is applied to clean, dry and non-rusty metal, it’s close to “forever”
In the right conditions, it doesn’t even need to be a petroleum product - a few years ago, a Russian tank was pulled out of a lake after being under water for about 60 years.
This airplane is in remarkably good condition after ditching into Loch Ness and being underwater for 45 years.
In the early 1970s I worked in a machine shop where we purchased, refurbished, and resold old machine tools (lathes, milling machines, etc.).
It was very common to buy machines that had been packed by the government at the end of World War II, clean off the grease and find them basically untouched by the 30 years in storage. So I agree that if properly coated and protected, the corrosion protection lasts a long time.
Funny looking ‘Russian’ Tank. 
The black/white cross looks German But still it is a Russian t-34. http://en.wikipedia.org/wiki/T-34
Would zinc be useful as a sacrificial metal to prevent corrosion of the desirable metals?
Yes, but it’s not useful on machine parts, because it changes the dimensions and properties of the part. In electronics, parts are often flashed with a thin layer of gold to protect against corrosion.
The article above the pics says it was a russian tank captured and used by the germans, thus the German Cross.
Zinc is used as a sacraficial metal on ships hulls, evaporators, condencers and other equipment.
I would like to point out that not all oils and greases contain lubricating properties. I packed a wheel bearing with what I thought was ordinary bearing grease, the bearing failed within 5 miles. I found out the grease I used was corrosion inhibiting grease, not a bearing grease. I replaced both bearings and used the correct grease and had no other failures. In my job building commercial aircraft, we use a variety of greases and oils. The packaging is color coded to insure we don’t mix the different types.
Unless you’re going to seal the item up, or coat it with cosmoline (basically petroleum jelly) you can expect to find that the oil will evaporate off, often within just a few months. I made a precision vise out of A-7 tool steel, and to keep it from rusting, I dunked in some machining oil. Within a few months of sitting in my toolbox, the oil had evaporated off and portions of the vise had started developing light amounts of surface rust. I’ve since lapped the rust off and dunked it in a rust proofing compound. Last I looked, it hadn’t begun showing any signs of rust.
But since petroleum jelly is, in my experience, hygroscopic, doesn’t that limit the “dry” life of an object?
It apparently has rust inhibitors added to it, and items protected with it are generally wrapped in plastic or waxed paper.