it started overheating check enginelight came on changed thermostat no change what could cause this p.s. blows cold air
overheating gets hot oil light comes on on 2000 Pontiac Sunfire
If the car is only blowing cold air, you might want to try bleeding the air out of the coolant lines. If that doesn't do anything, the heater core may be plugged.
Some possible causes are waterpump, cooling fan issue, coolant tempature sensor. If your oil light comes on its because your low on oil or past due for a change which should be a separate issue. Inspect for proper operation of fan(s) and if pump is making a squeal type noise replace. Otherwise try cool. temp. sensor replacement. Hope this will fix.
Also, as far as the oil light alone goes, it is possible that the oil sending unit is going bad. I'm not saying that it is likely, but that it is something to keep in mind. They are a pain to change if you don't have the right tools for the job. They should be rather easy if you have the right tools for this job and they aren't very costly either. Never hurts to start cheap.