On occasion, my 2003 Cadillac Seville SLS will indicate that the car is low on oil and I should stop driving. When I checked the oil, it has never been low. Prior to this happening, the gas hand began to dance between 1/4 of a tank and a full tank. I am not sure if these issue are related or if I have two separate issues. Any suggestions will be greatly appreciated.
I think you have two issues.
I think that the low oil sensor in the oil pan is going bad. It is an easy fix for your mechanic when you get your next oil change. After the oil is drained, the mechanic can replace the sending unit and then refill the oil and have you on the way.
The Fuel gauge could have a poor connection at the tank or under the dash. At worse it could be the float in the tank, which would require that the tank be dropped.
I agree with @Yosemite
However, I also suggest that your mechanic hook up a mechanical oil pressure gauge to your engine, just to make sure everything is good, before replacing that oil sending unit
The fuel sending unit should also be easy to diagnose and replace. If your mechanic has a good assortment of tools, he could hook up a resistance box in place of the sending unit float, and simulate 1/4, 1/2, 3/4 and full tank. The purpose is that he’s making sure the cluster is capable of reading the correct fuel level. With GM vehicles, 40 ohms is often empty, whereas 240 ohms is a full tank. Don’t hold me to those numbers, though.
And if the gauge shows the correct fuel level that the mechanic is simulating, and has a steady needle, then the float portion is probably in need of replacement. In that case, it’s best to replace the complete fuel module assembly, meaning the pump and the float.