I just got a 2019 Jeep Grand Cherokee with the 3..6 liter 4 valve engine. It with Pennzoil full synthetic 0-20 and I will keep it on that for warranty and free oil changes for 60,000 mi. It seems to run just as well and quiet as my daughters Caravan that is a 2015 and it called for 0-30. I don't really care for pennzoil but whatever is free is OK with me. If it were out of warranty I would use 5-30.I think I read somewhere when at normal engine temp most oil runs about like a 25 to 30w. I used M1 for many years from 15-50 to 10-30, but it just isn't the same anymore. The last two vehicles I used it it were noisy at start up and then quiet down. Going to try Rotella synthetic gas engine truck 5-30 in my 04 GMC Envoy. Heard great reviews on it and the car calls for 5-30. It tested a bit better than M1 5-30.