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Originally Posted by Old Tele man
...ALL EPA engine tests are mandated to be done using special 91 octane INDOLENE gasoline, with almost no sulphur content.
...so, not only is there no alcohol dilution, it's a mid-grade fuel, not standard 87 octane, low-grade fuel.
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Except the car company can recommend higher octane. For Federal certification, the minimum octane by research number is 93 and the motor number not below 85.5, so the minimum R+M/2 is 89. For 50 states certification based on CARB reformulated gasoline - the minimum R+M/2 is 91, except for this note
Quote:
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ii) Unless otherwise approved by the Administrator, the octane rating of the gasoline used must be no higher than 1.0 Retail octane number above the lowest octane rating that meets the fuel grade the manufacturer will recommend to the ultimate purchaser for the relevant production vehicles. If the manufacturer recommends a Retail octane number rather than a fuel grade, then the octane rating of the service accumulation gasoline can be no higher than 1.0 Retail octane number above the recommended Retail octane number. The service accumulation gasoline must also have a minimum sensitivity of 7.5 octane numbers, where sensitivity is defined as the Research octane number minus the Motor octane number.
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If the manufacturer recommends "regular grade" then the test can be done with 87 octane, but mostly the manufacturer can require premium and then use 93.
-mort