On Tue, 1 Oct 2019 22:46:33 +0100, Steve Walker
wrote:

snip

The spindle may well be an alloy casting.

More likely to be steel though. The body of the arm is more likely to
be 'pot-metal'.

I have never had any problem with copper-slip and alloys though. Indeed,
I have used it in a number of places where I had difficulty removing an
item, but have had no difficulty there after using it.

Same here (for lack of anything more appropriate at the time) but one
place I might be slightly selective where I might use something like
CoppaSlip is a wiper arm splines.

Specifically, if the arm has ever slipped before or the splines are
*very* fine then I might err on making sure it *doesn't* slip over
being able to get it off easily next time (which might be never).

Cheers, T i m