Just got a great deal on a used '05 4 door,4WD Explorer XLT Sport Edition(17" wheels,exterior trim etc)with 9500 miles on it from a Ford dealer. List new $34700 Paid $20600+tax with remote starter installed by dealer. This truck with employee discount and rebate is $27300. Love that employee pricing. Helped with this deal. The oil monitor says the oil has 74% life left. Does the monitor go by just mileage? Say 5000 miles?