Ok first of all I recommend you do not take down your knives to clean them as that is a great way to break them. Rather I have a better solution for you.
First buy some bottles of Zippo lighter fluid, the ones with the squirt top.
Use the squirt top to squirt the fluid into the pivot area of the knife between the handle scales and the blade. This will flush out any old oil and grime from the pivot.
Then use a drop of mineral oil (or nano oil or your oil of choice) on either side of the pivot. Just put a drop as that is all that is needed. Too much lube will attract dirt and will potentially cause that gritty feeling to come back again soon.