[Spridgets] VW fuel

[Michael Joy]

2003 VW Passat

Check with the dealer service department.  Many modern cars require premium
fuel for legal reasons... so they will meet the performance standards the
manufacturer advertises.

Since the spark advance is computer-controlled, it is advanced AND retarded
automatically to prevent detonation.  In MOST cases, it is perfectly
acceptable to use regular 87 octane gas.  The car might take 7.54 seconds to
reach 60 instead of 7.0, but that is about the only drawback, LOL.

The test for this is a simple one.  Let the fuel gauge get down to 1/2 and
fill with regular.  Now you have a full tank of 90 octane.  (Octane is linear,
so mixing half a tank of 93 with half a tank of 87 gives you a full tank of
90).  If it doesnt knock or ping, repeat the process at 1/2 full.  Now you
have a tank of 88.5 octane (1/2 90 + 1/2 87).  If it doesnt ping or knock, let
the tank get near empty and put in some 87, etc.