What might cause the oil pressure indicator to drop near low and the check gauges light to come on when warmed up and while idling below 1100 rpm on a 1995 Chevy S-10?

Depending on the mileage and mainytenance of the engine, you MAY be looking at an engine overhaul. First off, have you checked the OIL LEVEL? make sure it is full. If it is, you may have a failign oil pump issue. The oil pump is in the oil pan at the bottom of the engine and pumps oil throughout the engine. If the oil pump fails totally your engine will eventually seize becasue there is no lubrication between the metal parts. Not good. Now if your oil pump is working properly and you are experiencing low oil pressure readings, then likely the bearing passages on the crank are worn and you are looing at an engine overhaul. If the oil and oil filter in your S10 has NOT been changed regularly, then dirty oil has been recirculating throughout your engine causing premature wear on the bearings and pistons as well as valve train. This is why it is important to perform routine maintenance on oil changes. So...check the oil level and make sure it is full. Then......you can find where the oil pressure sensor is on your engine and hook another oil pressure gauge to it and see what that gauge is reading. If it reads low also, then you are looking at an overhaul. You can add a heavier weight oil to increase some oil pressure but that really doesn't cure the problem. You're using an oil that's too thin. The engine needs a heavier oil to maintain oil pressure as the bearing clearances get a little older. If you've been using a 5W15 oil, change to a 10W30 or even a 15W40. Try going up to the next heavier oil to see if that helps. If that doesn't do it, go higher again. It could be the oil pressure switch, they are very cheap and made of plastic, prone to failure. If you are sure you have proper oil pressure in the engine but the gauge on the dash says it's low, the first thing I would suspect is that switch.