

| Subject: | Re: Octane requirements |
| From: | David Beierl |
| Date: | Thu, 26 Aug 1999 09:30:52 -0400 |
At 05:58 8/26/99 -0700, you wrote: >Hey... have I been paying extra bucks for the 91 octane I'm put in my >"snugvagon" for no good reason? Is there any reason that I should not fill >up with regular? Hi James -- There are three things that distinguish super from regular: 1) higher knock-resistance, 2) higher detergent levels, usually, 3) *less* energy per gallon. If your beast is specified to run on regular -- my '84 is -- and does so without knocking, attribute 1 won't do you any good. The increased detergent, though, may help keep your fuel injectors clean, which is a win. However, I believe that as FI cars have become commonplace the detergent levels of regular have been generally increased to match premium. There was a lot of fuss about this 5-10 (?) years ago, but haven't heard much lately. If the price difference is 25 cents, then 25 gallons would equal the price of a bottle of Techron -- but you only use Techron every few thousand miles, so I don't think there's an advantage there. Assuming, of course, that premium gas would make the Techron redundant, which isn't clear to me one way or the other. By messing with the timing you might gain a performance advantage with premium, although surely nowhere near the difference in price. Cars with knock sensors (which Digifant does not have -- I think Digifant II may) can be adjusted to run optimally with premium but retard timing as necessary to run on regular. I don't know what tradeoffs there are, but this might be the best of both worlds. david David Beierl - Providence, RI '84 Westy "Dutiful Passage" '85 GL "Poor Relation"
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