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On 27 Nov 97, Allen Moore wrote: > Everett + Jennepher wrote: > > > > The Volkswagen 1500 with the twin-carburetor engine must be run on > < premium > > fuel with an octane rating of at least 95.*)" > > > > I assume this applies to all 1961-1967 carbureted T3s. > When was the last time ANYBODY saw fuel of that octane rating? (!) > Hoping 93 would work as well... There are two different scales for measuring octane: RON (Research Octane Number) and MON (Motor Octane Number). Each method has its proponents and good reasons to exist, but they are not the same. The gas at US pumps is measured by the average of the two: (RON +MON)/2. VW, however, when these cars were built, was using the larger of the two numbers. This works out to mean that the 95 that VW asks for is about the same as the 93 you can buy. No problem. At the time I don't think this was considered "high-test", as 98 and 101 or 103 were available. As octane has come down in an attempt to keep gas prices stable the best solution is to reduce your compression ratio any time you do a rebuild to accomodate what's now commonly available. This seems to work with no loss of performance. Jim --------------------------------------------------------------------- Melissa Kepner Jim Adney Laura Kepner-Adney jadney@vwtype3.org Madison, Wisconsin ---------------------------------------------------------------------