How "is" their skin?

There was a thread about rat tails awhile ago, and on it, someone mentioned that they put an oil of some sort on their rats' tails, to keep them soft and smooth. I have a very good, all-natural moisturizer that I use for myself, and sometimes I put it on Gus' tail, just so that the skin will be soft, and he will be comfortable.

But I'm wondering about the actual skin of the rat, under the fur. Usually, I'll just let Gus clean himself. His home is clean, and, like a cat, he grooms all of the time. Every once in awhile, I'll squirt him with some of that "leave in shampoo in a bottle," especially when I need to get lipstick stains off of him ( :lol: ) and a couple of times, after a big painting mess, he has had an actual bath in water. But usually, it's just left up to him.

He doesn't have mites, or lice, or anything like that - he's a healthy boy. But I notice that, when he grooms, sometimes, he'll scratch himself. I think it's natural, because I've seen my cat do it too, but it just got me to wondering how his skin feels. Do rats get dry skin like humans do? Is there some kind of "skin moisturizer" product for rats on the market, to keep their skin soft, supple, and non-itchy? Or am I just overreacting again? :lol:

Thanks in advance for the info!