I've never had very good results with a torch. I generally use my UT100 with a soldering tip, but a conventional soldering gun or iron better than 35 watts will work just fine with proper surface prep.

Control rods are coated with an oily substance that prevents rust, but I think it is a side effect of a lubricant used in the drawing process... not an intentional coating for our benefit, but rather a cost-cutting measure of bypassing a cleanign process.
Regardless, you need to go over the area of the rods to be soldered with fine emery paper, or even wet-or-dry (I use whatever I happen to grab).

One problem with a torch is overheating... getting the rods cherry red will soften them.