Why would oil leak from engine vacuum pump

This is probably unrelated to the oil change and just a coincidence in time. Very, very unlikely the oil change was the culprit in any way. My housemate has a 2014 Chevy Malibu with the 2.5L engine. He had a massive oil leak from the top part of the engine. We localized it to the area around the vacuum pump. A few posts on the internet suggested the vacuum pump could be the culprit, but I was skeptical. Nevertheless, I ordered a new vacuum pump for him. It's only 3 bolts to take off the pump itself, after removing motor top cover 3 Torx screws, etc. One of the bolts is a minor PITA because IIRC it's obstructed by a large coolant hose. Inside the old vacuum pump, there was a center round metal piece that was broken in the middle. Apparently because of that break, oil was going places that weren't tightly sealed. The new pump came with a new metal crush gasket. I had him spray both sides of that metal gasket with copper gasket sealant before installing. After replacing, the oil leak is gone. I'm putting this answer here to document that on 2013 and 2014 Chevy Malibu with the 2.5L 4 cylinder engine (and possibly up to 2016 or so) a bad vacuum pump can in fact cause a MASSIVE oil leak. Replacing the pump (new gasket included) DID in fact resolve the oil leak in this case. It's not a bad idea to supplement the new gasket with copper gasket sealant spray on both sides. Now I don't know how much he drove it with low oil, but the leak was so significant that he was down to basically half a quart of oil.