I'm a bit embarassed to admit this, but the filter is the cheap, probably unbranded one they use at Jiffy-Lube. I used to always change my oil/filter myself, but disposing of the oil became a chore I no longer wanted to deal with. I still do all of the other fuel/air filters etc.
I think I'm going try your suggestion, get a Wix and maybe maybe a bit heavier oil, and see if makes any difference. I think the oil recommendation for my '01 5.3 is 5W-30 or 10W-30 and that is what has been used.
For the boat I use the FL1A and SAE 30 oil. That of course I change myself!
1988 Tristar 190 Sport, 351W w/GT-40's, 1:1 Velvetdrive