This isn’t slide lock specific, but here’s what I do:
1. Clean off any visible gunk (adhesive residue etc.) on the blades/tools. Acetone (available as nail polish remover) works well, but avoid getting even residue on the scales.
2. Submerge the whole knife in fairly warm (but not too hot) water with a bit of dish soap. Allow to soak for an hour or so. Then work the tools open and closed under the water. Repeat this step if needed.
3. Submerge the whole knife in warm water. Allow to soak for an hour or so. Then work the tools open and closed under the water.
4. Final rinse under warm running water
5. Dry knife as much as possible with paper towel. Then allow to sit for a day or two to finish air drying.
6. Apply a very small amount of lubricant to the joints. I prefer mineral oil, and I use a toothpick to apply just the smallest amount. Then work the tools open and closed to distribute the lubricant across the joints.