Guess we might be talking to different mechanics then. The ones I spoke to before getting my Jeep and after told me to go with the 3.6 as they consider it to be the second best engine ever in a Jeep after the 4 Liter Straight 6.The internet is full of complaints with this engine. Just look at what mechanics are saying. Use super unleaded.
"So, is the 3.6L Pentastar engine reliable? Summing up, we can say the Pentastar 3.6 reliability is way above average. It is time-tested well enough, and over 10 million Pentastar engines were produced to date. Despite that they had some issues early on, the 3.6L V6 Pentastar is great, durable, one of the most reliable engines available on the market right now. With proper maintenance, the 3.6 Pentastar engine longevity is around 250-300k miles (there are even a few cases of the Pentastar last up to impressive 500,000 miles)."
Well you may not call it an issue, but there is definitely engine ping/valve rattle if I put regular gas (87) in my 19 or 21 jlu. You can easily hear it when you ride past something and the sound bounces off. I as a religion buy premium gas from Costco/BJs, since their premium cost the same as or less than everyone else's regular, so no brainer there.I’m hearing the issues with the 3.6 liter engine in the JL could be remedied by using super unleaded gasoline. That high build up of carbon could be the issue. Back in the day (1986) I never used anything other than super in my CJ7 and the engine ran quiet even with 158,000 miles.
I second this comment. I'd be interested in seeing a link or a document from Chrysler which recommends the use of Premium fuel for the 3.6 Pentastar for Model Year 2018 and newer vehicles. Automotive manufacturers do not take this recommendation lightly due to the litigious society we live in. Recommending the wrong fuel Octane has the potential to open the door to a class action lawsuit. So it will be interesting for me to see a document or link from Chrysler directly. If one indeed exists, I will happily switch to Premium.Where? The JL Owner's Manual certainly doesn't. The Grand Cherokee manual doesn't either.