Lube is almost always good and safe for starters. What type is not really too critical in cases where it is just simple stuff. If it were high dolar where we would not want to risk dirt and grit sticking in the lube we might get fussy. So I like spray lubes as I can get them into cracks and places where it might not be handy for other types but simple oil cans are good for lots of things if that is what you have. WD-40 is one that's always close by for me but tends to be thin and not last as long as a spray lithium or silicone spray.
But for a real cure, you may find the door is just a tiny bit warped and that may need to be moved over, just a tiny bit. If you can look at the door edge and see it is wearing and lube doesn't fix it, Perhaps a good solid nudge with the body or a rubber mallet may be more long term. Sometimes partly closed and stick a board in between the door and frame can move things enough. Use care not to knock the paint off something if doing this!
RV is the start of Really Very fussy!
2015 Winnebago Vista 31KE on 2014 chassis