What type of gas to use

[SVOboy]

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Your best brands are IMO Exxon, Shell and BP. The reason I say this
is that these companies are much more stringent (more stringent than
the govt requires) on the quality of the gas - i.e. corrosion
testing, particulates, sulphur compounds, etc. Also, they offer
additive packages that include detergents that are particularly
useful in older engines.

Your off-brands sometimes have "good gas" and sometimes do not. They
do not have the same quality requirements (internally - they still
pass govt regs but do not impose as strict internal requirements).
They buy what is on the market at the best price. Probably the reason
you saw the BP truck go across the street is that they had a surplus
and sold it to Racetrack. So at that point in time, you knew it was
good gas. However, they have many suppliers (may include the good
brands and bad brands) so the quality of the gas can vary a great
deal from week to week.

Even big gas companies buy gas from other sources but they still
require that it meet their internal requirements. I always buy Shell
(and now Exxon if I need to) because I know what type of gas we
produce and I feel pretty confident about the quality (I see the
certificates of analysis when we send gas down the pipeline and when
we load tankers).

Your smaller oil companies do not have the same requirements on
sulphur as the big companies (they were excluded from the govt
requirement to produce low sulphur gas).

There are other brands that make good gas but the 3 I listed are your
big players that I know produce quality product. I do not like Texaco
(except when I know that they just bought Shell gas) based on
knowledge of the refinery down the road from me.

- you can own an exxon station and you will use gas that is certified
by exxon (that gas may originate from bp but it must pass exxon's
requirements)

- you can own an off brand station and you may have a variety of
gas's at varying qualities, from week to week. if it comes from
exxon, great. it very well may not.

the difference is the internal requirements at the major companies -
they are more stringent.

also, the government has less strict sulphur requirements on gas from
smaller refineries/companies. if your off-brand store uses gas from
such sites, you are likely putting higher sulphur product in your
tank.

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Based on many years of record keeping now, I have seen that I get
around 1-2% better fuel mileage on Amoco/BP fuels in all my vehicles.
Unfortunately, it also pings like mad in my F150, but not in my Jeep.
I also get about 1.5% better fuel economy than average on Holiday
with no pinging. I also get above 1% better on Shell gasolines in
this market.

My worst performers have been with Sinclair, Mobil, and Kwik Trip.
Each posts numbers 2-3% worse than average.

Mixed bags are Phillips 66, Citgo, Conoco, Superamerica, and
Marathon. One vehicle loves em while another hates em. Note that even
Superamerica and Marathon, sole sourced from one refinery is in this
category.

My conclusions are that I do notice some differences in gas that are
measureable, but not all vehciles react the same.

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I can tell you with many years of record keeping over a small fleet
of vehicles, and knowledge of local gasoline sources, that my
vehicles DO have preferences.

I get 1-2% higher fuel mileage using Holiday and BP/Amoco gasolines
from the Twin Cities market. (Both of which are single source
products at different sources). I get 1 to 3% worse fuel mileage
burning Kwik Trip, Mobil, Citgo and Sinclair fuels, none of which has
a clearly identifable origin.

Some vehicles have different prefernces than others. One vehicle gets
+3% on Superamerica gas (single source product), while another gets -
2. Several brands fall into that category for me - Concoco, Phillips
66, Marathon, and Superamerica.

Also, while I get better than average fuel mileage on BP, I also get
pinging in three of the vehciles I've kept track of, so that isn't
optimum either.

Overall message: Keep good LONG TERM records and learn about who
supplies gasoline in your market (some are simple, others are not!)
and make a decision if there really is a difference or not!