I'm leaning towards a 5W40 or 0W40 for my upcoming oil change on my 2012 CTS 3.6 LFX. I'm currently running 0W30 ESP with about 4k miles on it (going to dump it at 5k). I am looking for an oil that quiets the valvetrain/DI high pressure pump ticking. Of all the oils I have used Redline 5W30 has quieted it more than others but I'm done using boutique oils since I never feel comfortable taking advantage of the long drain intervals that make them cost effective compared to the $30/jug high end offerings at Walmart. I'm thinking of using M1 FS 0W40 or 5W40. What 5W40/0W40 would you run to quiet a motor and also provide protection for high rpm driving? This will be my summer fill so low temperatures are not a concern. I will most likely hit my 5k OCI by fall and then dump it for another round of ESP 0W30 to get me through winter and spring.