Oil leak

Hi guys. When changing the turbo solenoid on Saturday I noticed oil has been leaking on to the sump guard. When I took it off my first assumption was it was leaking from the engine drain plug but the oil is three months old and it was a golden colour oil so not from engine. Is the IRD oil gold. I had the oils changed in the gear box and IRD about 3 years ago so it is not that old. Any ideas?. Ta, marty

Could be diesel , from the hp pump , I thought it was a oil leak on mine , but as said it was not dirty , and turned out to be diesel , came from drivers side of the engine , from the pulley area !