My chain has been rattling for about 3 months now but its a weird one.
Upon cold startup is sounded absolutely fine but after a couple of minutes it started to rattle like a diesel then after a few more minutes it would stop rattling and be fine for the rest of the journey. I had a service done last month and asked them to check it out but they said they couldnt hear anything and it should be ok but if it starts again to take it back and they would try to diagnose. I thought balls to that as they would charge me again for the privilage. So after reading all the posts on the cam chain section on this site I decided to call Vxl customer services and ask if there were any outstanding re-calls on my Astra (2001, just clocked 48000 miles) they came back saying that all re-calls had been done. I thought well thats strange so why the rattle if its got the new chain and oil nozzle etc. Well I ordered the cam chain and shaft balanced chain kits (thought well if Im getting one replaced get the other done too) from Autovaux on the monday and received them on the tuesday, at a substantially cheaper price than Vxl (£80 cheaper) and had them fitted on the thursday at a local garage my dad uses and what did I find when I saw the removed parts..... the old style chain and small oil nozzle.
As said many times on this site if in doubt get it changed. You'll know when your chain rattles it pretty obvious that it doesnt sound right. And for gods sake dont leave it as long as what I did I was exstreamly luck and constantly paranoid that mine would snap before I got it replaced. Now it sounds as smooth as when I brought it 3 years ago a seems faster too but probably cos before I was driving so causiously never over 3000 rpm.