And don't use the cheap Fram filters that fail at normal pressures?

Cut one of those open some time and you will see why. It'* a shame, because those used to be good filters. Now plastic and paper.

an engine is a stok. After warming up of engine sharply falls pressures of butter. Prompt me, that it can be? On a cold engine pressure 40.

pressure sharply goes down on 2 divisions

The pressure of warmed oil in a warm engine is lower than the pressure of cold oil in a cold engine. Can you estimate what the numbers of your various pressures are?

40 on a cold engine
20 on a hot 210F engine

at the purchase of auto did not change butter, replacement of butter can will help. I even not zanayu that is there inundated and when replacement was produced

in summer pressure was normal 40 and did not fall

speaking of which....

http://robertisaar.co.cc/1_15_FRAM-PH3980.html

i'm not sure what size you 3800 guys use, but the 3980 is the equivalent of the ACDelco PF52(useable on any 60V6 IIRC, but 3.1 and 3100 for certain), and the PH series is the caustic orange, low-buck version at that.

in ~1,000 miles or less, i should have a TG3980 to pull off and cut apart as well.

Yep, that'* about how it looked when I pulled apart a fram.

To answer a few questions you had in that write up.

The bypass valve is between the oil pump and the filter.

The oil pressure is taken after the oil filter.

So a sudden drop in oil pressure would indicate a plugged oil filter. Personally, I don't like this. I would rather know the pressure between the oil pump and the filter. And even better, 2 oil pressure readings, one before the filter, and one after the filter. Hmm, that gives me a thought for a mod when I build my new engine.

good stuff to know!

so that little leaf spring.... does it exist only to bypass the filtering media when there is sufficient oil pressure inside the cannister? i can't see it doing anything else.

Ya, that sounds about right, the filter plugs and it needs a way to bypass. I guess dirty oil is better then no oil. I have a old Fram in the shop. I should cut it open.

To answer the PF52 question, yes I use it on the Bonneville, and it'* pretty much the standard extra-long filter to use on any 60º V6 or 3800 or the new 3900 or basically anything of that sort. The PF47 is the stock filter, and you do need to use it if you have a W-body with just the wrong amount of spacing to stop you from using a PF52. If there'* no space constraint, I don't see a reason not to use the longer one. Also, I don't see a reason to use Fram. As much as they have the ability to filter oil and whatnot, and I'm not arguing that, I believe they have weaker bypass valves and those cardboard endcaps make me nervous.