Using Mobil 1 makes absolutely zero difference. Everyone of my Hemi powered cars have used Mobil 1 and everyone from time to time exhibit the "blue smoke" problem on start-up. We just purchased a 2018 Dodge Durango SRT8 and will less than 500 miles on the odometer it has the same occasional issue. I agree oil is probably leaking through the valve seals, but FCA has not been able to correct the problem and these engines have been in production since 2005. Every forum has a discussion on this issue and no-one has found a cure. It is just another quirk of these cars and having the local dealer arbitrarily replace parts to find the magical cure will put your vehicle in more danger.