Opinels are a great knife, they just need some attention when you first get them to make them more water/moisture resistant.
Take off the locking ring with a pair of snmall needle nose pliers, using the pliers in reverse to spread open the ring till you can slip it off. Now sand down the awlfull finish Opinel puts on them and when you finish the final smoothing out with 500 paper/0000 steel wool, finish with the Minwax stain and sealer of choice. When it has set for a couple days to a week, make the final finish Helmsman Spar Urathane. Two light coats with a very light sanding in between. Oh, and when you sand it, make sure you're getting down in the blade slot, and around the pivot area. Tape off the blade and move it to 90 degrees to sand around it. Make sure you take down the amount of wood around the blade pivot. Use a pipe cleaner to get the sealer down in the blade slot and around the pivot.
I used to use alot of linseed oil to finish, but it was very time consuming, and did not do as good a job. With the knife finished in the above method, I've tested them out by leaving them in a glass of water for 15 to 20 minutes, and was still able to open and close them. Durring the summer, we do alot of kayaking, and my Opinel is in my shorts pocket alot. Theres been times water has slopped over the side of the cockpit in windy choppy conditions and made my shorts wet. Later at lunch, I could still open my Opinel. It may get a little stiff, but even after being soaked it can still be pulled open.
I had the chance to speak with some real French guys, and they just take some vasoline on a toothpick and lube the pivot with that. Simple and crude, but effective.