I've had to blow the gear down manually once. The story about oil spraying everywhere is a myth, nothing of the sort happens.
However, because we didn't trust the gear even after blowing it, the pilot in the right seat got out of the helicopter while the pilot in the left seat (PF) kept the helicopter light on the wheels. The rights seat pilot proceeded to pin the gear before we lowered the collective all the way and taxied to parking to offload the passengers.