John L. - Octane/valve wear/hardened seats

["Thomas J. Harais" <tharais@domain.elided>]

John:

Well written piece on gasoline octane rating. Thought I might add two
small caveats.

1) Several years back, a local news station took samples of various
grades of gasoline from various service stations aroung the bay area and
had them analyzed. The results: Measured Octane was all over the place
(including some that was so low it was scary) with no direct correlation
to brand, grade or supposed rating.

Moral #1: Buy your fuel from a reputable (name brand) dealer that is
very busy. Otherwise the fuel sits around in the underground tanks and
picks up lots of contamination as well as making it's octane rating
suspect.

2) Consumer Reports along with some other periodical and newspaper
articles I have seen continues to profer the idea that all the major
gasoline refiners are putting the exact same additives in all their
grades of gasoline. But, by the advertising they are using, the
manufacturers imply that all the "cleaning" benefit of the additives is
in their premium grades, leading many consumers to utilize premium grade
gasoline in vehicles where it isn't needed.

Moral #2: Use only the grade that your auto/truck manufacturer
recommends octane wise, unless you have a very substantial reason
(measureable experience or modification) to do differently.

Personaly, I utilize only name brand gasolines with a full compliment of
additives in my fuel injected Honda to avert problems with the fuel
injection system. In my hot rod Z/28 (11:1 compression) I have found
that Texaco premium eliminated any pre-ignition the best of all
brands/grades, but this car was built before unleaded fuel anyway and
none of today's gasolines is really right for it.

The old IH: with low compression, large tolerances and two fuel filters,
I'll run just about anything in it. Sometimes I'm sure it would burn
kerosene! However, I have noted a need to fill it up with premium if I'm
going to climb long grades or pull a lot of wheight to minimize pinging,
especially if it's hot weather. But I have also found that if I go slow
and easy in those conditions, I can minimize pinging as well, without
resorting to premium fuel. Of course, I have never advanced my timing
past 0 BTDC because I've just been too lazy to try.

Tom Harais
'76 Traveler 304/727/20