Whatever you do, don't use 3-in-one oil or any other thin product. They are poor lubricants and don't contain anti-corrosion additives. When I moved back to Florida in 2008, I had a local shop service several of my reels. I asked him what he used and he told me 3-in-one "Which is as good as anything else". After a year the gears were grinding and needed to be replaced.
I now use Rick's Reel Service in Masaryktown FL (
http://www.ricksreelservice.com/. He has made sort of a science of repairing reels. We have become pretty good friends over the years and he has turned me on to Corrosion X products. He cleans everything inside and out with Corrosion X lubricant and uses Corrosion X grease on the gears. He used to use Yamalube Marine grease, but it may be too viscous for colder climates.
I get my reels cleaned and serviced every year or two depending on how much usage they get. Between services, I just rinse them off, dry them with a cloth, and spay them with Corrosion X. I'll use a drop of Corrosion X Reel Lube on the spinning reel bail rollers, handles, and any external moving parts. I have reels dating back to the '70's that are still running great. Had to replace a few parts of course.
That being said, I previously used Penn Reel Lubricant and had pretty good luck with it over the years.