in my 90 accord the oil light will come on when 1) low oil level is detected or 2) loss of oil pressure is detected. it seems you have determined that the oil level is fine and it is not leaking, so i would say focus on the oil pressure... could be something small like the oil pressure switch or even just the wiring to the switch. same type of thing happened to my accord last year. i was told by a mechanic that this switch was "bad." i didn't have them fix it but instead looked at it myself. knowing next to nothing about this i was still able to tell the wiring connecting to the switch was totally loose. i had a friend help with reconnecting this, or whatever he had to do, and its been totally fine ever since. im guessing the geniuses i got to change the oil (the week before this happened) knocked it loose maybe? these were also the same geniuses who LEFT THE OIL CAP OFF which i didnt notice until i drove 4 HOURS AWAY on vacation. same oil change too. luckily i found the cap sitting on top of my radiator.