You must check your owner's manual for the specifics. The manual will tell you the exact oil capacity and the recommended weight (e.g., 5W-30, 10W-40).
Looking at the oil fill cap or dipstick might give you a clue, but the owner's manual is the definitive source. If you don't have the manual, you can often find a digital copy online by searching for "[Your Engine Size] 1994 Jeep Wrangler Owner's Manual" (replacing "[Your Engine Size]" with the engine size, such as "4.0L" or "2.5L").
