It seems the more knowledge people have about firearms, the stranger their advice gets to a simple question. Basically if you bought a firearm that has a lifetime warranty, and it doesn't go *BANG* when you pull the trigger, send it back to the manufacturer. You shouldn't be worrying about too much or too little oil, this or that, or anything else brought up. In a SHTF situation the last thing you want is an undependable firearm.
I have a MAC-90 that has never failed me. Not once, no matter how poorly I treat it. I have been shooting it for around 25 years. However, my new S&W Sport II has been garbage so far. It's going back.