I've just joined forum and can tell you no oid pressure on start up on cold mornings is the seal between the oil pick up in the sump and the oil pump in the block going brittle and needs changing before you damage engine. Just done mine as happened once last winter and when is happened again this winter didnt use car until changed seal. Car is 2011 and has done 150,000 miles.I realise that this is a long while ago now, but did you sort the problem and if so what was it??
My 2012 Insignia does this and only on cold mornings!
Seal is just £11 but a major job to change but can be done by DIYer. Good video on YouTube.