Though I kno we are talking about Chevy trucks in here, I would like
to share a little experience I had concerning use of different
octanes, but on my dual carbed motorcycle. Though some might not find
it relevant, I would be that it does go to prove a little something.
Long and short of it is this, my bike is recommended at 87/89 octane,
however, since I have owned it I have (until recently) run nothing but
92/93, figuring I was "making things better."
Then I had been informed that I was actually costing myself money and
some power, of course I did not believe it. SOOO on a full tank of
92/93 I had it dyno'd wasn't the greatest numbers but what do you
expect from a little 600.?
Ran it dry, filled up with 87/89 for two tanks, after the second, I
took it back to the same place, dyno'd it again, and low and behold,
the hp jumped up. Now, I do not have the numbers handy, but when
talking about a little motorcycle weighing 500# a little more hp makes
a HUGE difference.
The moral here is that running a higher octane DOES NOT mean you are
going to gain anything other then a lighter wallet.