Just switched out my O2 sensor, cat, plugs, wires the other day and I notice now that my oil light will come on after maybe 15 mins of driving. If i keep the rpms up, it will sometimes go away, but is there at idle. Im hoping this isn't the oil pump, but should i just get a new sensor/switch. It's about 500mi. away from needing an oil change and the oil does feel a bit thin. As another question, I have no owners manual so what should I use for this time of year in ny with 120k on the engine.