Some folks don't mind a little "honest wear" on their guns from being holstered and taken afield. Others want them to look new for decades.
One thing you can try, especially with a lined holster is to wax your guns instead of oiling them on the outside. Oil will get into the lining and collect dirt, grit & grime.
After a good cleaning and lubricating, remove all oil from the outer surfaces. Isopropyl Alcohol will work when applied with a patch or soft cloth. Apply a good carnuba based wax over the exposed metal surfaces. You may need some Q-Tips for certain areas. Buff off when dry. Some folks use Renissance Wax but cheaper products like Flitz Rifle/gun wax and plain Johnson's paste wax work too.
The wax forms a barrier against moisture until worn off. In a holster, it adds a slickness to the surface without oil to pick up dirt. Wax that rubs off can be brushed out of the holster's lining.
BillCA in CA (Unfortunately)