my peugot bxer 1999 had water ingress into the gearbox?

I have a Peugeot boxer 1999 1.9 turbo diesel with xud engine.it suffered water ingress and changing gear became awkward,i fixed the water problem and put oil around the selectors it has eased a lot but does anyone know if I keep doing this it will go back to normal or do I need to open the box up?has anyone out there had this problem?

paul j
May 2016