Oil - even a very light oil like sewing machine oil or 3-in-1 - isn't likely to do much good. This is where you want a penetrating lubricant like Liquid Wrench, WD-40 or LPS-1.

Wipe off the oil you've applied, take the tire, tube and rim strip off, and apply a drop of penetrating lubricant at both sides of each nipple. Then let the wheel sit overnight (or at least 4-5 hours). After that, if some of the nipples will turn but some of them are still stuck, IMO it's worth it to try a second drop on those.

With any luck, that'll buy you some time to where you can rebuild the wheel on your own schedule, or at the very least you'll be able to get most of the spokes out without using snips. But the bottom line is once there's corrosion in the threads, they'll continue to corrode. You can often clean large fasteners with Scotch-Brite and/or a wire brush, but spokes, well...