No, it isn't mine (thank G-d!)

Since I've borrowed a tensiometer and was planning to check and tighten up my home-built wheel, and check my other wheels while I'm at it, my dh decided he should maybe take a look at his rear wheel, which has been making rattly noises for a while. He's used it for commuting daily, through the 3 last winters, and rides trails with it too so it's seen hard use.

The wheel was fairly round and straight but the tension was awful, no more than half of what it should have been. But almost every single spoke is stuck. Turning the nipple, by screwdriver or nipple wrench, just made the spoke wind up, even when holding the spoke with a wrench. We dabbed a drop of oil on each nipple in advance, to no avail. They look visibly corroded.

Can he expect to be able to loosen these, or should he just go buy a new wheel, and plan on rebuilding the original wheel with new spokes? I'm not too optimistic about oil being able to work its way into those tiny threads.