At 07:12 PM 6/13/2001, mike miller wrote:
>And putting in higher than called for octane does nothing for you unless you
>have an ignition system that can adjust timing on the fly based on knock
>sensors.
>
>Just what he said but sounds corrects.  David B you want to weigh in here?

Who, me?  I agree with you, a higher octane than the engine needs does
nothing for you.  Under normal conditions our WBX engines should run
correctly on regular, although the manual does stipulate that higher octane
may sometimes be desirable for "heavy-duty use" or words to that
effect.  But if it's not pinging (and doesn't have a knock sensor retarding
the spark), any extra octane number is wasted.

Fuel-injected engines can have trouble with injectors fouling; certain
intake-valve deposits can cause stumbling; combustion-chamber deposits
raise emissions.  Since 1995 all gasoline sold in the US must contain
sufficient detergent to keep injectors and intake valves clean -- but not
necessarily to clean them.  Some gasolines contain enough detergent to
clean valves and injectors, and *often they are the higher-octane
grades.*  Also, as of 1998 only the Texaco Clean System 3 (r) and
Chevron/Oronite Techron (r) detergent systems were effective in cleaning
combustion-chamber deposits (this last ref:
http://www.colin-houston.com/Press_Releases/US_Gasoline_Detergent_Additives_1997-2004.pdf
).

As to whether it's cheaper to put a bottle of Techron cleaner in a tank of
regular every 5-10k miles, or use several tanksful of high-test with the
same detergent package, I dunno.

David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"