I changed my oil about a month ago. I put in Mobil 1 syn 10W-30. I had only put in about 4 1/2 qts due to the fact that I am retarded and forgot to drain both plugs. Anyway, my check oil light comes on periodically. I checked the dipstick and it was a little low. I added another quart and the light still comes on from time to time. Any ideas why this happens or suggestions to what I should do?