Got around to my gearbox oil change. Both filler and drain plugs came out without too much resistance. Glad I changed it, it was old. Slight green tinge but fairly dark/black. Put in new Millers Pistoneeze classic gear oil EP GL4 80W90 and it now shifts more smoothly. I took out about 1.8 litres so put back in the same. Took it out for 30 miles today on an essential trip and hse drove lovely.