I’ve started servicing my Mk2 - first time I have been under a car for many years and thoroughly enjoying it. Engine oil, oil filter, air filter and plugs done so far but before changing the final drive oil I’ve got a little confused as to what the right spec is. I have a litre of Mobil SAE 75W-90 which I ordered from mx5parts but the Haynes manual says this is correct for the transmission but that the spec for the diff is SAE90 GL5. So I am confused - do I have the right oil for the diff or not? Having looked through the forum I think the answer is “yes” but would appreciate someone who knows more than me! Thank you.
If the bottle says GL5 use it, if it says GL4 do not use it. I guess it says GL5.
If it says GL4, just go to your nearest shop tha sells oil and get a litre of GL5 oil that is at the cheapest price. It matters not if it is 75W/90, 80, 90 or 80/90 as long as it says GL5 and it matters not if it is mineral, semi synthetic of fully synthetic.