I have a 1990 4-Runner V6 4x4. The whole undercarriage and engine compartment of the vehicle are covered in oil. Also I am having to put a couple (Usually 3) quarts of oil into it every 3 weeks. I have heard that it maybe the gasket on the back of the oil pan leaking to where it is dripping on the drive shaft and then the oil is getting thrown around.. Does anyone have any ideas of what it could be? Also is this a common 4-Runner issue? Thanks for the help.