GMC Repair: oil gage, oil leaks, oil pumps

Question
i have a 91 cavalier, 6 cylinder.  my car is a one owner, well maintained.  i've had it for about 2 months.  the check gages light was coming on & it was out of oil (there is absolutely no history of oil leaks; the car belonged to my mom before she gave it to me).  i put in oil, have been keeping an eye on it.  the gage says it's 1/4th full, but as i drive it the gage drops & the check gages light comes on.  someone mentioned an "oil pump"--i never realized cars had oil pumps?  could it be the oil light sending unit?  any suggestions?  the car did sit for about 2 months before i started driving it.  thanks

Answer
Carol,
Check the radiator and see if there is oil in the coolant. Does the car run ok? Any smoking out the exhaust pipe? Could someone have drained the oil before letting it sit? The oil has to be going somewhere. The oil light could be faulty, (that is why the call them idiot lights). If there is no oil in the coolant I would make sure that the level on the dipstick is full and if you have to place a piece of cardboard under the engine when you park it overnight and the next morning see if there is oil spots. Let me know. Thanks and sorry it took so long to respond. Jeff