My sister’s Cruze popped check engine light. Its the stupid valve cover/integrated pcv valve. Its freakin cold at the time and I am busy at work. I say, just take it to this (reputable) shop. They put a new valve cover on. I get a call next day about smell of oil burning. I look behind valve cover and there are pools of oil on intake manifold. “Take it back.”. She calls me next day and says they tell her oil pan gasket is leaking, not their work from earlier. I told her “yes, small leak in oil pan gasket for years, thats not the cause of the oil smell. Tell him to look behind valve cover.” They have her leave the car, hear nothing for two days. I go down there and ask whats going on “tech says its the oil pan gasket.” I look behind valve cover everything is clean. I ask for the keys, go on the highway for 5 minutes, return to shop, bring service writer out, get a flashlight and show him oil all over the back of engine pouring out of valve cover. “Oh, we’ll have to fix that”. “Thank you”
A couple years ago I had successfully replaced the very same valve cover gasket (it had started to leak) myself. Follow instructions in shop manual, dont go hog wild with gasket sealer at seams, all is well. Like said above, a lot of times when someone else does your work you get screwed.