I have a 2001 Astra with the Isuzu diesel engine. Whenever I start the engine from when it has been left for an hour or two, the oil pressure light takes about 5 or 6 seconds to extinguish after the engine starts. Is this normal? Does anyone else's do this? On previous cars that I have owned, the oil pressure light goes out straight away.
Could it be that oil is draining out of the oil filter when it has been left standing? The filter is a cartridge type and is located at the top of the engine. Does anyone know if there is a non return valve fitted somewhere in the system?
Perhaps this is just normal. Somebody please put my mind at rest!
Vauxhall Astra 1.7DTI Oil Pressure light -
I have the same type vehicle as you and when I bought the car I noticed a distinct delay too. I even posted abouted it too about 18 months ago.
I wouldn't say mine has a 5 to 6 second delay, about 3 to 4 would be more accurate. It had 38K on it at the time and it's now has 84K. I change the oil and filter meticulously every 5k and is still the same.
I never suffered any problems so I've put it down to a characteristic of this engine, so perhaps you're right, with the filter sitting almost vertical at the top of the engine compared to at the bottom of every other car I've owned.
Hope this helps, or at least tells you you're not alone!