On my son's 1998 Dodge Dakota the oil pressure gage constantly swings from left to right. Is this a sensor problem or some other problem? Thanks

Oil pressure will constantly fluctuate, depending upon engine speed, engine temperature, and oil viscosity. If the needle is erratic, check the gauge (provided it's a mechanical oil pressure gauge); otherwise, check the sending unit. Start using full synthetic SAE 5W-30 engine oil. It will safely clean the engine and provide a substantially higher margin of safety. Sludging engines will show low or no oil pressure. Change synthetic oil and filter every 6,000 miles or 6 months, whichever comes first.

They are usually located on top of the engine, close to the firewall. Engineers try to keep them close to the valves, which are last on the oil train and the first to go if there's an oil problem.

Where is the oil sending unit located on a 1998 Dodge Dakota? I have looked everywhere and can not find it. Thanks

Check AutoZone Part No. PS358. See if you can find it then.