Yes Peter that is the impression I have got . It appears that these gearboxes are not too fussy about what type of oil is used so long as the correct ammount is there . Thanks for everyone's input
I've been using the Penrite HPR 20 60 full zinc ten in both motor and box as Penrite specify. I must do a check on the gearbox level soon though as it has the dreaded seal drip. Thanks for warning.