Vauxhall insignia top end noises

[Kay]

Hi all I’ve got a 2018 Vauxhall insignia, I’m hearing a noise now and again from the top end can drive for weeks and not hear nothing then suddenly it makes a noise for a a couple of hours and then goes again. I’m trying to find out if anyone have had this same problem and what it could be. I guess probably the hydraulic tappets and lifters possibly sticking or could it be starvation of oil getting to the top end. It’s a 1.6 diesel.