I switched the wife's 04 MDX to synth a few months ago. Computer did
not show any increase in mileage whatsoever.

I use synth in my lawnmower. High stress, non-pressurized, gets real
hot in summer (especially if the air fins get blocked by grass
trimmings at times). $2 worth of oil in a $200 lawnmower once a year.
That's extravagant, but probably more useful than synth in a car
engine.