Red Green wrote in
:

About 18 months ago I put in a new Borg exterior steel door. A month
ago or so the flexible vinyl(?) strip on the bottom of the door that
meets the fixed plastic(?) bottom squeaks when you open and close the
door. Kind of like the sound rubbing dry fingers over a dry balloon.

I tried both spray silicone and vegetable oil and the squeak returned
shortly afterwards.

There have been no issues with the door closing, latches and locks
becoming difficult or door edge/jamb gaps so I don't believe movement
is a contributor.

Other suggestions?

No, I haven't tried WD40.

Lots of good suggestions I never thought of. Glad I posted the Q.

Haven't tried anything yet but one that popped into my head was furniture
polish maybe?