Stiff rear window zip

 On rare occasions I put my hood up and find that the window zip is very stiff .Is it a good idea to lubricate it and if so what with.I realise that a broken zip is expensive to replace so I don’t want to get it wrong.Has anyone got any instructions from hood suppliers on this subject.Any help greatly appreciated.

Kev

I have used soap on a zip before now.

Silicon / silicone (which???) spray would be good if you could administer it with spraying everything else around it also!

Maybe vaseline? - but would the petro-chemical part of it affect surrounding materials?

 Traditionally either candlewax or a graphite pencil will help a sticking zip.  Plus both are a bit easier to apply than anything sprayed on.

 Thanks Lola and Goof for your suggestions.I might also consider WD40 but at the moment the hood is down and car in garage after a good cleaning session today and a nice blast around the countryside.