[Shotimes] Octane requirements and old engines

[Leigh Smith]

I agree that normal winter regular fuel seems to work well in my SHO's too.
The reformulated summer version gas seems more in-consistent (NJ) regarding
pinging.
Two other common pinging issues regarde engine condition: both carbon build-up
and oil consumption (past rings/valve guides) raise the octane requirement of
an older engine considerably.
There are top engine cleaners out there that work very well at de-carbonizing
the piston tops. (The GM one is fabulous).  I used it at six month intervals
on my '89 SHO once it went past 150k and it made a slight difference in less
pinging. The SHO has less carbon build-up and/or is less susceptible to this
sort of pinging than other cars I have had & seen.
However, once the engine starts to burn oil, it pings more, so you just have
to use better gas to stop the pinging. Once it burns enough oil that it pings
on 87, try 91, etc. Once it pings a lot on 93, then it's engine rebuild time.
Never reached that point on my 280k mile'89 SHO, however it didn't like 87
octane any more, it pinged too much, so it was starting to go, so I ran 91 or
93.  (Ahh gee...only 280k too)
I had an older 4cyl that died at 189k, the rings just quit within 20-30k
miles. It pinged so bad at that point, even on 93 octane with octane booster,
it sounded like pebbles in a coffee can; non-stop. That engine was rebuilt and
it needed nothing except a new set of rings, which were shot. The plug tips
were very heavily oil-coated, so it was just the oil making it ping.
Our SHO's are definately built better than that. IIRC I heard the rings were
chrome. That type of ring last a long time, as we have seen.
Lee