Acording to my 1987 plus 4 handbook (gemma box) it's
Castrol hypoy ep90, or duckhams 90s. Or texaco multigear ep 85w 90
Hope that helps but it is the handbook that came with the car so I can't be absolutely sure it applies to the gemma box.
Nick

Last edited by nick w; 04/08/22 08:19 PM.