I was given an old rifle that says 22LR Smokeless Greased ammo. What is this? Will modern 22LR work in this gun assuming all else is in good condition?

22 rimfire ammo was originally black powder. It meant your rifle was to be used with Smokeless ammo with lubed bullets instead of black powder cartridges. I think most if not all factory 22 ammo is lubed or waxed. Some more so than others. They just don't put greased or smokeless on the boxes anymore.