Guys, I finally got around to checking my oil pressure with a mechanical guage today after the oil pressure alarm came on once more... the news is bad - the mech guage was reading 15-20 psi at idle when hot which I think is dangerously low. The problem I have is whether the problem is oil or oil pump... The pressure on cold start up and while driving normally seems to maintain around the 35-40psi mark. It seems to be when driving it hard and then idling it will drop down to the 15-20psi mark. Is this a symptom of poor oil (Magnatec 15w40) or a worn oil pump? I have tried thicker oil (20w50) and different brands but it doesn't make much difference. I would really appreciate some comments on this as I'm thinking this could be a rebuild on the way...

It's not always oil or pump, it could be worn internals, especially bearings!

Does it ever rattle in the bottom end?

Theres certainly not enough noise in the engine to worry me in terms of big end knocking, it is slightly rattly on start-up for a brief second (still minimal though). The minute the lifters pump up its all good. Do the pressures seem abnormally low or not... ? The car has only done 152000kms which I don't think excessive at all.