If the refill is in situ.. Find a type of 1 litre oil bottle with a nice long spout and use that to fill the gearbox. Keep the last one with the 0.5 litres of spare oil in it.. next time refill it from your new oil in bottles with stupid short spouts, and use it again..
I had that thought and decided to drain mine and put a newer super duper oil in that came very highly recommended on several old car / banger forums. Spent a lot of money on the new fangled stuff too. Within a hundred miles and maybe even less my gearbox was squealing like a pig. Ran it for several months like that then decided too change it back to regular 80/90 or similar Millers oil which I bought instead of Morris after a skinful one night. Took a while like several months but the squealing gradually calmed down to mostly like it was before I put that synthetic stuff in. Too much detergents perhaps ?? Too many additives perhaps ?? Who knows Ozziedog,,,,,,,,,,,,,,,,,,but my box did not like it one little bit.
Castrol Syntrans (whatever it's called these days) will do nicely. Quietens your box down and improves shifting
That was exactly the oil that I was talking about. I reckon there’s a bit of Daz or Omo in there that cleaned and loosened all the grunge out of my box. But as you say, it’s got a great reputation on several forums. Ozziedog,,,,,,,,,, maybe I was just unlucky
With a recon gearbox the synthetic stuff has been fine for several years now, it has quietened down nicely with a bit of running. (Not that it was as loud as when it went off for rebuild, but given the way the couriers dropped it almost upside down on the way back, it might have altered shape very slightly even though it was the bell housing that got hit)
Recently had my transmission rebuilt but I haven't put any oil in it yet. I will be using EP 90 grade and I think it's castrol. Still a long way off yet but will report back though.
Put some oil in it now, its easier, or a big label on the gearstick reminding you- one or two people have forgotten this bit over the years...
Castrol Transmax Transaxle 75W-90 is one of the best lubricants for our transaxles currently available. https://www.opieoils.co.uk/p-6363-c...e-75w-90-fully-synthetic-transaxle-fluid.aspx