I took my 2018 Silverado in for an oil change. The mechanic said that there was a lot of oil in the air filter and that he cleaned the oil, but he did not have time for a diagnostic. I took my truck in to another local place who did the diagnostic and concluded that the PCV valve was bad and needed replaced. They said it's covered under warranty still and that I should take it to the dealer.

I took it to the dealer (it's been about three weeks since the issue was identified). They said there was oil in the air filter again. They cleaned it also. They said that the PCV valve needed cleaned, so they cleaned it, and charged me the hour diagnostic fee. Had the $15 valve been bad, it would have been covered under warranty? What gives? Is cleaning the PCV valve something that I should be doing?