What oil for rear diff?

[myfirstE21]

hi all,

does anyone know what oil i should put in the rear diff of my 316? i want to change it as it looks like its never been done?

cheers
steve

[nas80]

you can use pretty much anything - 75w/80 or 80w/90 etc etc.

[myfirstE21]

sweet 80/90 it is then as i have loads at work

cheers !

[E21meister]

Very timely subject - just done my gearbox (75w/80 to GL-4 spec - don't use diff oil) and diff (75x/90 GL-5 spec) oils today. I've always used Castrol as this is one aspect of maintenance you don't want to be using budget lubricants on.
And I'd do the gearbox oil at the same time if I were you. The gearbox oil in mine smelt like it had last been changed around the time England last won the World Cup, it had probably burned at some point. Gives you an excuse to clear of all of the swarf on the drain plug magnet too.

[tommi_e21]

is there any oil additves for differentials like slick 50???

[E21meister]

is there any oil additves for differentials like slick 50???

Amsoil was a favourite back in the day, did make a difference in a knackered old 'box I had in a Mini I had once:
http://www.amsoil.com/storefront/fgr.aspx

You could always try this stuff:
https://www.xadoshop.co.uk/shop/catalog ... IOzhukzGxO
More of this teflon type snake oil by the looks of it. I'd pop a bollock if it worked but you never know. Personally I wouldn't put any additives in a gearbox/diff unless it's completely shafted and you have no other choice.