When I buy a brand-new Frying pan, the instructions usually say to "season" or oil the Pan. I just purchased one and it also says to "season" after every 10 dishwasher cycles. I always wash my pan by hand, so do I need to do this every 10 washings? What is the purpose of "seasoning" the Pan
"Seasoning" on non-stick pans is quite different from seasoning on older frying pans made of things like cast iron or carbon steel. For something like cast iron, you are trying to create a durable coating of polymerized oil, essentially a "non-stick layer" of burnt oil. That process of seasoning can require a lot more effort and specific steps.
Your non-stick pan doesn't need that, since it already has such a coating that is resistant to sticking. But you still can benefit from an occasional lubricant to smooth out any microscopic irregularities in the pan's surface and to serve as an additional chemical barrier between the surface and the food.
This New York Times article has a good summary of care for non-stick pans. The author interviewed a number of manufacturers of non-stick pans. To the relevant section:
So this is what I should have known. I should have “preseasoned” the pan by rinsing and drying it and rubbing it with a paper towel with a little oil on it. Pretty much any type of oil will do.
It’s a good idea to rub about a teaspoon of oil or butter on a cold pan each time you use it, Mr. Winter [director of research at Nordic Ware] said, because despite the name nonstick, most of the cookware needs some kind of lubricant.
Just don’t pour oil or butter on the pan and then slosh it around (my method).
“Then the oil is not adhering to the pan but being absorbed by the food,” he said. Not only will you have butter-soaked pancakes, but after a while they’ll start sticking because there’s no grease."
And later in the article:
Although I don’t usually put my cookware in the dishwasher, I did as a last-ditch effort — another bad idea. Most experts I talked to said to hand-wash nonstick cookware, because the high heat and harsh detergents can ruin the coatings.
To answer your specific question: oiling periodically may or may not be required. It depends on how you use the pan. If you frequently cook with oil or butter and only handwash the pan, oiling may not be necessary at all. If you rarely cook with oil or fat, you may find it helps to rub oil on the pan once in a while.
Using harsh detergents will be hard on the pan's surface, as the above quotation says about using dishwashers. If you're handwashing, I'd just do it "as needed." That is, if you notice your food sticking a bit, then wash the pan, dry thoroughly, and rub a tiny amount of oil on. (Note that there's little benefit in leaving excess oil on the surface.)
I rarely use non-stick pans these days, but when I have, I never bothered with "seasoning." As long as you handwash and cook with oil or fat, you may not need additional oiling at all.