The point isn't check if it exists, check if it seals. The simplest check is valve cover seal and that half moon rubber bit. Don't just look at it, look around it. See if there is fresh oil coming from it or under it. If not that, wipe it down and just let it idle and stare for about 10 minutes and assess any new oil buildup. In my experience, the 22r/e motors run better than most engines for longer, but they leak like a bandaid in a public pool. Clean it and trace it. That's all you can do. Alllllll of my parts are leaking and it doesn't matter I just fill them.haha if your head gasket is blown you'd know it.
oil inside sounds like an EGR problem, or blow-by in the piston rings. It'll run, just not as well as it should. Good luck