my buick lucrene is front wheel drive. went to change oil the other day and notice oil under the car starting at the motor and all the way down the passenger side of the car. it does not leak when the car is parked while running only when you drive it. checked oil pan and bolt and no signs of leaking oil. notice lot of oil around large pulley on side of motor. so i think its the seal. and also if this is the problem do i need to pull the motor.