Hit it right on the nose. It was an observation I've made. I like the heavier 40wts myself, but I drive my cars hard, fluids are changed sooner than later. My 4cyl Honda I found the same thing online. Heavier weight oils, but seemed to prefer a 0/30 over a 0/40. That k24 series engines uses a timing chain, a little heavier oil will leave more of a film behind than of a 20wt. Also that car has a 5sp manual. At 80mph rpms are at 3100, no thanks for a 20wt especially during the summer.
Bullwinkle,what oil are you running in your Honda? My apologies if you're already mentioned it,
Currently I run Castrol 0/40. I also wanted to mention, especially during the summer heat in nor Cal, the idle is super smooth with the AC on. I don't have an oil pressure gauge, but my experience, the oil pressure is slightly higher at idle than a hot 20wt. Back in the day I had a built 2180 dual carbs in my 65 vw bug, that motor was pretty radical, 295 cam duration at .050th , 725 lift with ratio rockers. Idle had to be set at 1500, and still loped hard. That engine did not like a 10/30. Ran M1 15/50. This M1 was from 1995 era