You MUST check your owner's manual. This will specify the exact oil type and viscosity recommended by the manufacturer. The manual will also tell you the correct oil capacity for your engine.
Without knowing the engine size, any recommendation here would be a guess and potentially harmful to your engine. Using the wrong oil can lead to decreased performance, engine damage, and costly repairs.
If you don't have the owner's manual, you can often find a digital copy online by searching "[Your Engine Size] 1989 Dodge Caravan Owner's Manual". You can also find this information by looking at a sticker under the hood (though it may be faded or gone).
Once you know the engine size, you can then search for the specific oil recommendation online or consult a trusted mechanic.
