> You snipped the Mercury Marine 89 octance fuel reccomendation from my note
> for stern drives ....
No, I didn't, since it wasn't in the message I replied to,
but while we're on the subject:
Mercury Marine's 89 octane recommendation is a manufacturer's
recommendation, yes? When the manufacturer specifies an octane
rating, by all means use that as a minimum. My Volvo Penta stern
drive needs 93 octane, so that's what I run.
> The 89 octane recommendation also comes from my Chrysler
> dealer and my automotive mechanic...reasoning is the same regarding the
> quality deterioration of regular gas.
What quality deterioration in regular gas? Octane rating has nothing
to do with quality, though the oil companies have done a very good job
of subtly marketing otherwise. As a matter of fact, I've gotten wildly
variant quality same-octane fuels (based on pinging) at same-brand
stations. Unfortunately, you rolls your dice, you takes your chance,
when it comes to fuel.
> Carbon buildup will also occur in 4 cycle engines.
Nobody claimed otherwise, but using quality of 2-stroke oil as a
data point for running higher octane fuel is beside the point.
> I have driven in the US and have
> noticed significantly differences (ie. pinging) in 'regular' gas depending
> upon where I bought it. I don't believe that 'all regular is created equal'.
You and I are on the same wavelength, since my experience is
identical. But I doubt you believe that 'all premium is created
equal,' either. Bad gas is bad gas, and that is why I typically keep
meticulous records of my Dakota's gas usage and remember to avoid
stations that sell bad gas.
Buying premium grades can often mask questionable fuel. I've had
to buy black market no-name "93 octane" gas under duress before, and
the Dakota ran worse (less mileage) than it did when I ran my usual 87.
> I'd rather pay a few cents more at the pump now, than a major engine repair
> a few years from now.
So you're buying premium gasoline as insurance, which is fine with
me. Whatever makes you feel better. But that doesn't mean regular
gas is by definition worse quality, which seems to be your implication.
Octane rating == antiknock capacity, nothing less, nothing more.
Some manufacturers do provide different additive packages in different
octane fuels, so that can factor in to your decision. But the fact
remains that all gasolines sold in the US are legally mandated to
contain additives to fight fuel system deposits.
> take care of the equipment and keep it for a long time.
Sage advice, which everyone should live by.
> By the way, my wife's Sundance pings like mad on 87 ... Chrysler recommends
> 87 for that car.
Chrysler's octane recommendations seem to be typically low, judging
from the testimonial evidence I've gathered (many people with CC
products complain about pinging when running manufacturer's octane
rating). As a matter of fact, my Dakota pings when I run 87 _winter
formula_ fuel, so I usually run 89 octane during the cold months.
And then back to 87 when it warms up.
Let me reiterate my main points, because I don't want this to
escalate into the typical Usenet flame war:
1. You must use fuel that allows your engine to run without
pinging.
2. Engine octane requirements depend on many factors, including
design and maintenance. E.g. running plugs with too high a heat
range, or carbon deposits in the head, can increase an engine's
octane requirements over and above the manufacturer's recommendation.
Octane requirements within an individual engine line can often be
different (my Dakota might need more octane than your Dakota).
3. Once an engine's octane requirements are met, increased
antiknock capacity (octane rating) has no added value for your engine.
4. Some oil companies offer different additive packages in
different octane fuels, e.g. Chevron with Techron/Techroline in
their premium fuel only. However, all gasolines sold in the US
for highway use must contain additives that control or inhibit
fuel and intake system deposits.
5. The most cost-efficient method is to experiment with different
fuels, and stick with the lowest octane, best quality fuel that meets
your engine's octane requirements (doesn't ping).
6. If #5 seems like a pain in the ass, then run premium fuel if you
like.
7. Blanket statements like 87 octane fuel == worse quality, 93
octane == better quality, are incorrect.
No offense meant, no offense taken.
Ron
P.S. Whenever I get into this discussion, I like to refer to
http://www.cis.ohio-state.edu/text/faq/usenet/autos/gasoline-faq/
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 12:07:55 EDT