UK Car Repair: whirgling sound from the engine on astra G, low oil pressure, oil gauge

Question
It seems that you are right. Oil light operates on contact as it should, but I was skeptical about it staying on for about 10 – 15 seconds after start and then goes of. It doesn’t light in driving, oil level is fine, filter has been changed. Could it be the oil pump? Can I check the oil pressure? What do you suggest? Can this damage the engine?

-------------------------------------------
The text above is a follow-up to ...

-----Question-----
My 2003 astra G 1.7 tdi has rapid whirligig sound coming from the engine when it is cold. It is present for about few minutes (probably until heated a little), and then goes away. It sounds like sharp and increased normal sound of valves running. Astra obviously has a louder engine with those fast “clicking” sounds, but this is sharper and louder. Otherwise engine is working smoothly and without any problems.
-----Answer-----
It sounds like an oil pressure problem at start up. Does the oil gauge/light operate as soon as the car starts? Have you checked the oil level?


Answer
YES! Low oil pressure is very serious. The "lazy" light indicates a loss of pressure somewhere. It can be checked with someone with a gauge that connects to the Engine, most garages have one.  You could try using a different oil, a higher viscosity 30/50 or plain 30W. Perhaps even a synthetic.