On my rather old tube of 'regular' Araldite it says it is ok for metal.

If this is so then why would I ever use one of those 2-part adhesives
sold specially for metal? I mean the sort of thing that is usually
coloured grey and can often be bought in car accessory shops?

I need to glue an aluminium ring (about 1.5 inches diameter and about
4mm thick) to a plastic base. There will be some light to moderate
stressing of this arrangement when it is in use.

I figured the Araldite was just fine for the plastic but what about the
metal?