Hello, just a basic question. 2015 Malibu LS 2.5L engine. My oil cap says to use Dexos 5w20 oil. I have only ever had the dealership do the oil changes ever since I bought it new. Had one done today and was looking over the work order. It says they used 5 quarts of Dexos 5w30. I never took notice before what they used, so they may have used that since the first oil change. My question is, does this have any negative effect? This is a Chevy dealership, so you’d think they’d know the proper oil to use in their cars.