Hi,
First thing to do it take it apart and check.
If the oil is leaking on top of the transmission then it will get oil in the clutch and will start to cause problems with it spinning.
If the oil leak is from the side of the transmission were the coupler is then it could drip oil there for a long time before the washer ever starts acting up.
To repair any leak you will have to replace the transmission.
This video guide will show you how to get the washer apart.
Video: Whirlpool Made Direct Drive Washer Motor Coupler Replacement