I think i have found your problem dude. like it.
Like this one too.
https://www.youtube.com/watch?v=LqZqjc2aNfo&ab_channel=InitialDave My 97 discovery had to have sump off, and 30mm deep solid tar chiseled out of base of sump, and strainer cleaned. Was bringing oil light on when warm, strainer had only 3 openings left open in it, should have known before buying, she had "oil changers" stickers on her.
Grief, why even bother to flush it.
Sump off at that point.