I could be doing it all wrong, but I never remove the side plate. Did open one once when a new revolver had a problem, just to see if it was obvious, then sent it back to S&W.

About every 500 rounds (three range trips) I put a single drop of Hoppe's Bench Rest 9 Lubricating Oil with Weatherguard in the Hand window and another on the Cylinder Stop.

Using Gunsmithing screwdrivers, I remove the cylinder as part of my after shooting clean and lube.