I got my 2018 Scat Pack (Automatic, with just under 20K miles) a few weeks ago and in the first few days I noticed that the engine was knocking. I figured the dealer put in regular gas so on the next fill up I made sure to put in 91... still knocking. Added STP octane booster and it got much quieter. Now it sounds like a ticking. I'm wondering if the ticking is something different. Here are 2 possible conclusions I am working on. Hypotheses #1 - The 6.4L runs better in the 93-96 octane range than it does in the 91 range and even thought it's 91+ most gas stations are closer, if not under, 91. Anyone know which gas stations are better for higher octane? I live in California, near Oakland, in the San Francisco Bay Area and there are not any 93+ octane gas station nearby (all are 87, 89, 91). I would rather not have to use an octane booster every time I fill up but I also don't want my engine to knock. Does anyone use the higher octane bottles, like the race gas number (96, 101, etc.)? I'm wondering if I can buy a bottle of 101 and just use half or 1/3 each time since it's around the same cost as the STP. I admit, as much as I am a DIY mechanic and have been working on my own cars for over 20 years (plus Auto shop in High School and College), I'm not very well versed in how the octane boosters work. Will adding a full bottle of 101 be bad for the car or a waist? Hypotheses #2 - The ticking I'm hearing is because of the oil the dealer used and not related to the knocking from the 91 octane gas. The 6.4L doesn't like the dealer oil and something like Mobile 1 Synthetic would be better. What oil is everyone using in their 392 engines? I used Mobile 1 Synth in previous vehicles and was going to do the same on my next oil change but if it will stop the ticking I might do it sooner. Anyone else have similar experiences with their 6.4L engines ticking or knocking? Do these engines just tick all the time? My understanding of car engines is that they should not, but I don't have experience with HEMI engines and heard somewhere someone mention the "HEMI Tick".