While 5W-20 might be *acceptable* in some cases, it's not universally recommended. Your owner's manual is the definitive source. Check the manual for the specific recommendation for your engine and climate. Using the wrong viscosity can harm your engine.
If you don't have the owner's manual, you can often find a digital copy online by searching for "[Your Engine Size] 2000 Ford Ranger Owner's Manual" on a search engine. You can also check the sticker under the hood, which may list recommended oil weight.