Date:         Sat, 17 Sep 94 21:02:16 CDT
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         "J. Walker" <JWALKER@ua1vm.ua.edu>
Subject:      regular vs. premium: a new war errupts!! :)

well ... ray said he thought it was better to buy premium gasoline for your
bus. i choose to think that, while he may find it better for HIS bus with
the gas in HIS area and HIS style of driving, it is better for ME and MY
bus to run regular.

why?  well ... just intuitive interpretation of years of experience and
keeping track of the data. for the buses i've had, and the gasoline i've
bought (and gasolines can vary considerably from region to region, according
to the magazines and gas companies), it just works out 'better' for me and
my wallet and my bus.  when running premium octane, i get no increase in
economy or performance ... but then, i don't change the way i drive with the
octane in the tank. :)

anyhoo, here's the data (summarized) if anyone is interested. i added the
last column (miles/dollars) to see if ray's idea might prove valid, but it
doesn't seem to (for my driving, my bus, my area's gasoline). also don't
forget that ray has a 5-cylinder and my bus is a 4-cylinder ... it might make
a difference.
-----------------------------------------------------------------------------
  Saturday, Sep 17, 1994      20:43:11                      Page    1
 OCTANE - Fuel Data Summary  by  Octane, Brand
 Octane Brand  Tanks  Gallons     Cost       Miles   m/gl   $/gl   m/$
 ------------- -----  -------   -------  ---------  -----  -----  ----
 r87 amoco        25    335.8    359.84    6,815.2  20.30  1.072  18.9
 r87 bp           27    343.5    367.43    6,779.6  19.74  1.070  18.5
 r87 chevron      26    354.2    384.73    7,013.0  19.80  1.086  18.2
 r87 exxon        27    371.7    396.81    7,267.1  19.55  1.068  18.3
 r87 shell        43    554.8    614.83   10,795.5  19.46  1.108  17.6
 r87 unocal       26    363.3    370.70    6,961.7  19.16  1.020  18.8
 r87 z-other       1     13.6     15.22      275.2  20.24  1.119  18.1
 r87 z-start       1     15.7     14.10        0.0   0.00  0.898   0.0
     r87 Total   176  2,352.6  2,523.66   45,907.3  19.51  1.073  18.2

 r89 amoco        12    159.5    167.47    3,056.4  19.16  1.050  18.3
 r89 bp           11    160.0    176.95    3,161.0  19.76  1.106  17.9
 r89 chevron      11    153.8    179.71    3,072.2  19.98  1.168  17.1
 r89 exxon        12    164.0    176.48    3,101.2  18.91  1.076  17.6
 r89 shell        12    163.6    180.18    3,130.8  19.14  1.101  17.4
 r89 unocal       12    158.2    173.21    3,035.4  19.19  1.095  17.5
     r89 Total    70    959.1  1,054.00   18,557.0  19.35  1.099  17.6

 p92 amoco         6     83.7    104.75    1,564.4  18.69  1.251  14.9
 p92 bp            6     78.6     95.08    1,527.1  19.43  1.210  16.1
 p92 chevron       6     73.9     93.73    1,472.3  19.92  1.268  15.7
 p92 exxon         6     62.2     76.94    1,312.8  21.11  1.237  17.1
 p92 shell        10    128.6    149.04    2,566.5  19.96  1.159  17.2
 p92 unocal        7     88.8    107.67    1,767.2  19.90  1.213  16.4
     p92 Total    41    515.8    627.21   10,210.3  19.80  1.216  16.3

 Total           287  3,827.5  4,204.87   74,674.6  19.51  1.099  17.8
 Per Tank Avg            13.3     14.65      260.2  19.51
----------------------------------------------------------------------------
what i get from these numbers is that
(1) my bus and driving style don't seem to care what octane the fuel is; the
    economy stays pretty much the same (i don't consider plus/minus 0.5 mpg
    as 'significant': what with speedometer errors, filling errors (not to the
    same exact level each time), density of fuel (cold fuel vs warm fuel),
    etc.)
(2) as the price goes up, the miles/dollar ration goes down. so the premium
    is a waste of money for me.
(3) all this is pretty subjective anyway, since the data is NOT scientifically
    very accurate. we are talking about gallons and tenths, and miles and
    tenths (about 500 feet!), and poorly paid, untrained labor. :)

now what YOU do NOT see is
(1) there are only three (3) companies in town that provide wholesale fuel.
    and they all sell to all the stations. so amoco sells fuel to chevron,
    and shell sells to bp, etc. so there very likely is NO physical difference
    in any of the brands i use.
(2) certain stations are closer to my house than others (shell), so i bought
    more of that (before i started trying to 'even up' the brands/octanes
    to see if there really was any difference). and certain other stations
    are closer to the interstate ... so i would be much more likely to fill
    up with chevron/bp/unocal just before a highway trip. but i have tried to
    equalize the city/highway ratio as much as i can.

the best 'rule of thumb' i've heard is to run the cheapest octane you can
THAT DOES NOT MAKE YOUR ENGINE 'PING'. usually, this is what is recommended
by the manufacturer. but not always. i currently also own a h*nd* (shame!)
for which 87 octane is recommended ... but it pings on local 87 octane. so i
'have to' run 89 octane in it (to get what i consider 'normal' running and
performance).

anyhoo, them's my data. for what it's worth.   it's your bus, your money,
and your choice. :)

joel
the old pot-stirrer