You need Castrol MS3 not LM, (at least according to my tin of MS3 which is
now 34 years old, and I originally bought to pack the replacement CV joints
on my first two minis!!)

Wasn't it also needed to change the Mk1 rear sub-frame assembly, the one
that had the rubber cushions? I think that's why I bought my tin, which
must be approaching the same vintage.

It must have been a victim of the EEC/HSE or whatever... I seem to
remember my father had a very old tin but what he used it for I don't
remember... Just the sort of thing you can't get in small quantities
so it stands for centruire gathering dust in the shed...