85W90 gear oil:
5ltr Napa (and others) £30
5ltr Swepco 201 Multi £120
Are you racing your defender across a desert or driving for hours in Arctic conditions ?
Crossing mountain ranges that are actually volcanoes ?
Will you be spinning up your axles for extended periods doing many hundreds of miles a day on twisty racetracks ?
Entering a drifting competition ?
Do you enjoy spending loadsa dosh for no real benefit ?
Are you easily led by slick (see what I did there ?) advertising ?