Use 5w-30 and don't worry about it. I think 5w-20 would work with it fine ..but that's just me.
Brand is up to you. How long do you want to leave it in service and what's your annual mileage?
ENGINE: 3.7-LITER, SOHC, 12-VALVE SMPI POWER TECH V-6
* Availability: Standard – Renegade and Limited Edition, Optional – Sport
* Type and Description : Six-cylinder, 90º V, liquid-cooled
* Displacement: 225 cu. in. (3701 cu. cm)
* Bore x Stroke: 3.66 x 3.57 (93 x 91)
* Valve System: Chain drive, SOHC, 12 valves, roller followers with hydraulic lash adjustment
* Fuel Injection: Multi-point fuel injection with returnless fuel rail
* Construction: Cast-iron block, compacted graphite bedplate, aluminum cylinder head
* Compression Ratio: 9.1:1
* Power (SAE net): 210 hp (157 kW) @ 5200 rpm
* Torque (SAE net): 235 lb.-ft. (319 N•m) @ 4000 rpm
* Max. Engine Speed: 6000 RPM, electronically limited
* Fuel Requirement: Regular unleaded, 87 octane (R+M)/2
* Oil Capacity: 5 qt. (4.7-Liter)
* Coolant Capacity: 14 qt. (13-Liter)
* Emission Controls: Catalytic converters, oxygen sensors, on-board vapor recovery system, leak detection pump system(a)
* Max. Gross Trailer Weight (lbs.): Automatic with trailer tow package 5000 lbs. (2250 kg) Manual transmission 3500 lbs. (1600 kg)
* Estimated EPA Fuel Economy mpg (City/Hwy): Automatic 17/21, Manual 16/22
(a) Meets Federal Interim Tier 2 B in 9A standards and is a California ULEV I under California Cleanest Vehicle Rules in CA, NY, MA, ME and VT.