yes, you should change oil every three monthsoil looks clean doesn't mean oil is still in good condition, if you drive in city at most time, the milage won't be high because the car is running at low speed mostly, but in fact, the oil has being stayed in high temperature for long time, high temperature would change the oil to be "bad"
this is my 2c only, follow it must take your own risk
-gogo_go(流浪的丑狗);
2005-8-15{352}(#2452808@0)