My '90 535ia has the common low oil pressure light syndrome, so today I'm gonna inspect the pressure sensor and oil canister anti-drain check valve.
Within the past couple of months somebody posted some excellent pictures and procedure for repairing the spring that controls the oil anti-drain check valve. I've searched the archives, to must be using the wrong key words, so cannot find the post.
The procedure involved the anti-drain spring that keeps the oil from draining from the oil filter.
Can someone please direct me to that excellent post and pictures of this procedure?