“ 97 Tahoe with 40K rebuilt 5.7, FWIW”
Fram filters would let pressure drop at idle to zero and gradually drop to 20 at 2000 rpm highway. 10W30 non-syn.
Switched to WIX or Delco and problem went away . YRMV.
do you remember which fram you ran? they have 3 or 4 levels of filter, and I wanna say the one for the older Gen one sbc had the bypass in the block, well in the filter adapter housing but didn't need one in the filter. these ls need one in the filter. so totally different and much smaller setup.
for a while the best fram was considered the best bang for the buck. but I haven't kept up. someone said they changed a bit. might not be any more
my 96 had 325k on it. never rebuilt, had literally whatever oil I had laying around for free and whatever the cheapest filter was, anything from stp to wix thrown on it over the 20 years of driving it. and it never had any oil pressure issues. like every other sbc I've been around. oil is just not an issue, they just run till you scrap the truck. these ls engine oiling systems while seem better on paper. see all kinds random issues. gm even had to come up with a half dry sump for the track model cars and they can still run dry on long high g turns. the drift kids that swap ls engines rod knock the first 3 before they realize they need $3k in oiling system to keep them alive.
then they somehow made it even worse on the LT with pumps themselves failing.
man I miss the Gen 1 sbc when you didn't have to worry about anything. 50hp more at a rpm I never use in a suv for all the extra hassle feels silly when I type it out lol.