Do a search of past postings. There have been several discussions on Penrite. I've had it in my 31's steering gear box since last summer. Works great and stopped the leaking of lubricant. I drained the steering gear box and then filled it with Penrite. I'd recommend it if you have any lubricant (600W)leaking from the gear box.
Obviously I'm not from down under. Just passing along my experience with the product.
I have an F100 box it my Vic that leaked 600W like a sieve. I waited until it was about empty and filled it with Penrite last summer and it stopped leaking.