I don't know but what Ed has something specific in mind, but I wouldn't use a spray lubricant on the fins. Any standard one will leave a dirt-attracting residue, and you don't want plugged fins and dirty tubes. PTFE (teflon) and dry silicone won't leave a residue, but they don't prevent corrosion either - they just leave a powder coating that can sluff or wash off. Rather than trying to keep some coating applied, I'd just take Ed's advice and remember to lightly hose down the radiator when washing the coach and especially after leaving an area of sea or road salt exposure.
Most radiator cores are either aluminum or copper/brass, both tubes and fins. I guess there are some that have steel or perhaps aluminized steel fins. I was of the notion that ours were aluminum, but I know many large truck cores are copper as were I think at least some Country Coach ones. Copper/brass exchanges heat better, but the softer metal means the tubes can't be as wide or they'd tend to collapse, so more tubes that are narrower are required, i.e. - the same size copper radiator with 4 side-by-side tubes might only have 2 tubes if it were aluminum instead. Thus, copper cores are heavier, a disadvantage when you're a coach or truck manufacturer trying to save weight. Copper also tends to corrode easier, partly because aluminum forms its own defensive oxide layer on its surface. There are all kinds of considerations to take into account between the two types of core construction.
The area where your corrosion is showing looks like it could have encountered prior damage of some sort. That might have exposed the fins there more by knocking off protective paint, I don't know. Exactly why either aluminum or copper would display orange corrosion, instead of white or green, I'm still researching. I associate rust with steel.
Joel
Addendum: Out of curiosity, I have an inquiry submitted to an American manufacturer, and so far he is indicating that the fins themselves are not likely rusting. Rather the rust came off something else, which eludes to my contention that some iron composite device was up against the radiator at that proximal location somewhere along the line, or currently when installed on the coach. The rust stains can also have originated with a leak of some sort of poor, improper, or engine-stained old antifreeze. But the pix imply to me that the staining is from a proximal steel engine component or something.
If so, your core may be perfectly fine aside from some bent fins. Stay tuned.
Hey, was that Seattle game fun to watch or what?! Go Seahawks.