Probably as many opinions on this as there are types of guns!

Here's the way I would approach that. For this time, clean the gun after so Dad knows you're caring for it. That's probably the most important thing here. Then, when you return it, ask him if that's what he would have wanted.

If you're gonna be using his gun, you're gonna need to use his rules. When you get your own, then you'll need to decide for yourself what process you're gonna go through with cleaning and when.