Try Mendel's 5-minute rule. Works great. (and while you're at it, stick a pressure gauge on those 4 round rubber things.)
Earl always checks his earl. However, I don't get that cannot see the oil on the stick anymore with earl changes. Are they using a lower quality earl or skipping the filter? Earl
On level ground, pull out the dipstick, wait a good 5 minutes (in case there's oil drawn up the guide tube) then reinsert, pull out and check, in good light, both sides. Still seeing nothing?