"Larry W" wrote
Without delay, change to synthetic.
Run the engine up to temperature on same dyno, half hour later, sample
and print.
...snipped...
133 HP to 137 HP.
I doubt it would show up on the quarter mile time, but hey, I was
surprised.


There may well be something to that, but it would not be unusual to
have a 4hp variation between runs even if NOTHING changed.

Back in the '70s I used to do a fair amount of tinkering with model airplane
and race car engines. Synthetics were fairly new at the time and we
experimented. It was common to pick up a few thousand rpm and use less oil
in the mix. Made me a believer, as did the ME that I did this stuff with.