My 91 explorer has 175,000 miles on it. It still runs great. Yesterday the "check oil" light came on. The pressure gauge reads normal pressure. The oil is full, fairly new (500 miles - with a new Fram filter) and very clean.
What would cause the light to come on when all seems OK?

 

does the light come on and stay on or does it go off and on from time to time? Also do you got an actual oil gauge that gives you a reading if so does the oil pressure ever seem to drop when light comes on? Im guessing here but maybe you got a oil pump pick upscreen getting clogged by engine sludge or maybe you got somthing in the oil pan thats actually getting sucked up to the pick up screen and temperarily slowing the flow of oil to the pump. I had that happen on an older car that had aplastic type material coated around the camshaft gear and thats stuff cracked up and fell off and down into the oil pan after about 25 to 30 years. I had the factory oil pressure sender unit andlight,and a after market gauage at the time well the light would come on from time to time but being that it didnt happen that often it took me a few days to catch it but one day i did i seen that oil light come on and as soon as it lit up i had just a second or so to see it but the gauge reading dropped to like 15 psi for a split second triggering my light to come on. Anyhow Im not saying this is whats wrong with your car but it just sounded similer to that past problem of mine Hopefully you have some kind of short or somthing though im sure you aint wanting to here anything about getting into taking the oil pan off this soon in the game.. best of luck to you

 

Don't your Explorer have a low oil sensor in the oil pan? If so it sounds like you may just have a bad sensor here.