I believe jp15 has oil finished neck(as same as jp6).
But my jp6‘s neck got dirty as I play it for a long time. It has stains all over the back of the neck.
Does jp15 have the same problem?
Well, if your neck is getting dirty, you can clean it !
For cleaning the necks, I use the Ernie Ball Wonder Wipes and it's perfect after that.
Some people on this forum did the "oil & wax" treatment, but I never felt it was necessary (my Morse is 23 years old ...). I prefer to keep the "well worn" feel.