1uz, reasons for no initial oil pressure?

[George]

solved, it was the overly bent sump as I guessed. Had no chance to see it until I actually undone the sump. There was too little clearance between pickup pipe and sump bottom, so the thicker (coldeR) the oil was, the harder it was to suck it through that small gap.

[4th surf]

I actually had the opposite problem yesterday George. the hotter it got the lower my oil pressure esp as Perth is now approaching summer temps of 35 degrees C plus. Solution? oil change and add an extra litre as my sump holds 11 litres with filter.

It is funny how "Rotten sod" translates without loosing it's meaning, it does in quite a few languages such as Tagalog (Philippines), Afrikaans, German and so on

[George]

Let's see how it goes in summer time. Previously I ran my 1JZ on 'zic a+' and had no pressure issues (other than the light didn't come off for ~2 seconds, which is normal for the JZ), though every summer we do see day temps up to say 33 C here in Moscow (though we consider it to be extremally hot, this sort of weather can easily stay for a couple weeks), not to mention my trips to the Black Sea and back.

I'm quite satisfied that the rotten sods who spoiled my speed party are residing somewhere in logistics company, and the guy who actually sold me the engine appears to be just and honest.

[4th surf]

Yes but George you can swear in russian and I cannot. I have picked up a few terse words in tagalog from the wife but can speak no other language other than english. Oh and you can probably get an AK47 a whole lot easier than I can

[George]

Most of times I need not any of the things you listed )

[4th surf]

From reading your posts and how you've helped other people... You're a good man George... Thank you.. Take this post as it is meant which is with a great deal of respect

[allencr]

solved, it was the overly bent sump .... There was too little clearance between pickup pipe and sump bottom, so the thicker (coldeR) the oil was, the harder it was to suck it through that small gap.

No, it's not the pickup-to-sump clearance or thick oil. If it was that bad it would have lost pressure at 1500rpm and all the bearings at 4000.
It's like 4thSurf wrote, the pickup pipe broken weld/s or bent flange -

...pushed up and cracks the welds on the pickup allowing an air leak and thus longer to pick up on oil pressure.

[George]

However all of the issues are gone after ensuring the proper sump clearance. Namely, the warning light goes off instantly even after the car has been left on cold for one day, and the oil pump does never produce the terrible sound it used to. I will check the pressure at high rpm just in case however.