I know there are many very informative posts out here related to oil. Very informative, but I’ve made no conclusive headway in a situation I have. I purchased a used 2013 with only 32,000 kms (20,000 miles) on it. I’ve put 10000 kms (6,000 miles). The dealership changed the oil at purchase using AC Delco Full Synthetic Dexos. The salesman told me to change it at about 7,000 kms. His thoughts were it really was only a synthetic blend. I did change at 7,000 kms at a local spot that is owned by and Petro Canada that uses Petroleum Canada Premium full synthetic as their top premium oil. I googled it and it is dealer approved. I have put on 3,000 kms since the oil change and Ive noticed the engine has become a louder and there is a tapping sound somewhere. Quite possible I started to hear this about 2,000 km ago and it’s more noticeable now. Can’t really tell for sure but decided to start with the oil. I decided to go with a change. Couldn’t get into the dealer for a week. Figured I’d go today and decided to go with Mobil 1. Went to a different oil change location as they have an oil change package using it. I explained my situation. They checked the level and said that Cruze is known for this tapping. Didn’t really sound much different than the others they get through their location. They also mentioned they sell indentical AC Delco the dealership would have used when I picked up the car. I opted to go with that so I could have an apples to apples comparison of how the engine sounded with the original oil back in it. I’d say there is an improvement. It runs a bit quieter and the tapping seems more muted, but is still there. It still isn’t as quiet as the day I picked it up... it sounded like a new engine at that time. It was worth the cost to me to do this. I kind of hoped, didn’t really think it would completely eliminate the tapping but hoped for a better result. I figure I’ll give it 5,000 kms before the next oil change and get it to the dealer to have a look next week as I have the extended warranty. Did I make the right choice in going with the AC Delco over Mobil 1 for the reasons of the apples to apples test? Next change should I go with Mibile 1 and should I do it with sooner rather then at 5,000 kms And is this tapping really common on the 1.4? And is there a solution for it? Thanks in advance.