I too strongly recommend LPS-3. There are several versions of LPS and
you want version 3. It sprays on as a thin oil like substance but
some of the solvents evaporate and it becomes more waxy. It is a very
good product designed specifically for the very purpose Matt has.
CRC is a brand and produces a couple dozen different products. Some
of the CRC products are spray lubricants and would be inappropriate
for providing long term storage protection. CRC's SP-300 and SP-400
are the corrosion inhibitors. The 300 remains oily and the 400 dries
more waxy and is a better long term protectant. This was probably
Jerry's friend's recommendation. Its been a long time since I've used
the SP-400 and I didn't use it that much since I am so pleased with
LPS-3, so I can't really say how good the 400 is but it is similar to
LPS-3 as I recall.
WD-40 is great for cleaning off the waxy protectants, but DO NOT use
WD-40 to coat the mill to protect it for any duration. WD-40 is a
poor corrosion inhibitor. Some of the distillates that initially
provide modest corrosion inhibition eventually evaporate and after
awhile the remaining ingrediants (those rust busters, penetrants,
etc.) actually get a bit corrosive and provides less lubricity. In my
shop WD-40 is only used as a cleaner for small tasks since it's in a
handy spray can and it's cheap.