Did you check the owners manual?
I looked it up, 2018 Jeep GC owners manual, pages 445 & 446
Engine Oil Viscosity (SAE Grade) — 3.6L Engine
Mopar SAE 0W-20 engine oil approved to FCA Material
Standard MS-6395 such as Pennzoil, Shell Helix or equivalent is recommended for all operating temperatures. This
engine oil improves low temperature starting and vehicle
fuel economy
If they've decided a full synthetic is required there should be an OM addendum or TSB.
Synthetic Engine Oils
You may use synthetic engine oils provided the recommended oil quality requirements are met, and the recommended maintenance intervals for oil and filter changes are
followed.
Synthetic engine oils which do not have both the engine oil
certification mark and the correct SAE viscosity grade
number should not be used.
Chrysler MS-6395 approved oils linkyFWIW, to me, synthetic oil and nitrogen for tires are of quite dubious benefit, and considering the cost, given a choice, I wouldn't pay the difference. Near 50 years ago I was a mechanic, I've NEVER seen an oil failure, seen plenty of lack of maintenance failures. Just keep the oil and fluids changed. 2¢
