Richard Ewald wrote:
> Oxygenates are added in some areas in the winter to combat the extra
> rich conditions associated with cold start and warm up. (Oct thru
> April IIRC) I have read that oxygenated fuels do tend to give a
> little less MPG.
Thought I might have had that backward. You are correct.
>
> I can tell you that different fuel will cause some cars to run
> different. Back in the mid 1980s there was a large change in fuels,
> and the car make I was working on had start and stall problems. Many
> of these could be fixed just by getting the customer to switch brands.
That was 20 years ago and, as you said, fuel was being dramatically
reformulated. Doubt there is as much diversity now. I've only had
trouble with one tankful--BP brand--which I attributed to water. It's a
good idea to buy gas at a station that has high volume--the fuel should
be "fresher."
> If you still have doubts Google Top Tier gasoline and read the
> results. Chevron was the first (and I believe) the only brand that
> did not have to change its formulation to get this award.
>
> However I doubt that any gas will make a difference in day to day
> driving. If you drive long term on poor fuel, it could have a
> negative effect due to plugged injectors, valve deposits etc. I
> suspect a case of confirmation bias. The GOB bought the good fuel, so
> he drove a bit slowly, less jack rabbit starts etc, and guess what?
> He got better mileage.
Agreed. When FI first became common there were problems with some
brands that did not have correct or sufficient additive packages. I
believe the additives have since been mandated for at least minimal
injector maintenance.
Some think "Top Tier" is strictly marketing:
http://forums.corvetteforum.com/showthread.php?t=1431187
> For my daily driver, I run Chevron, Shell, or Union 76.
There was a time Shell gas had a bad rep (I've had no problem with it).
I agree over time the additives package MIGHT make a difference, but
tank-to-tank you won't see a real variation in mileage (there are too
many other factors to be totally objective). I stand by my claim that
the base stock--probably 99% or more of the fuel--is from only a few
refineries and is the same except for octane rating and additive package.
>
> $.02
> Rick
>
bs
***************************************************************
Bob Spidell San Jose, CA bspidell@comcast.net
'67 Austin-Healey 3000 '56 Austin-Healey 100M
***************************************************************
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