Drain the box..Top up until the oil is visible in the filler 'spout'...Use an SAE 40 or SAE 50 weight 'straight' oil as used for the engine....Ian

email (option): ian@wright52.plus.com

Thanks Ian
Willdo 😉

email (option): rwalsh53@gmail.com

Ian, would SAE 40 or 50 oil be better than the thicker gearbox oil ?

BSA specify engine oil, not thick gear oil or grease. Ron

email (option): ronpier@talk21.com