From memory it is only the early boxes that used EP90 oil and they had a threaded fill plug whereas later grease boxes had two smaller holes with rubber bungs in them.
The downside of the grease is that over time as it dries out it won't lubricate the innards properly but I would suggest you top up the grease until it comes out the other hole and then go lock to lock to expell any excess just to ensure TRW filled the box properly as I've heard of these being bone dry from the factory.
madness is in the eye of the beholder 👍