Wilber and all,
The stoichiometric A/F ratio for gasoline and diesel is almost the same by mass. 14.7: vs. 14.5:1. However, the auto ignition
temperature for diesel is lower than gasoline and lube oil auto ignition temperature is lower than diesel, hence the potential
risk of detonation. Also, the released heat by combustion in BTU/gram is almost the same across all hydrocarbon fuels. Look, I'm
getting a bit tired of repeating myself on this subject. I thought I would just slip this oil thing into the group because it
isn't common knowledge. Guess what....it isn't common knowledge. For all you doubters look it up yourself, Wiki is your friend.
Steve

"Wilbur Hubbard" wrote in message anews.com...
"Ron" wrote in message news
On Mon, 25 Oct 2010 14:23:46 -0400, I am Tosk
wrote:

In article 29b625b4-9ffe-4736-b512-dff137d6aa81
, says...


haven't figured out what it was, but I shipped it:


Also, I've never seen oil being more subject to explosion/flash than
gasoline.

How does adding oil to fuel make it more volatile?
L8R
Skip

Your comment and question shows a basic lack of fuel and combustion
concept understanding.

Yeah, I gathered he isn't a internal combustion engineer so what's your
point? I worked on cars for a long time and really never thought about
ping as it relates to two stroke fuel/oil mix, I just mix it right and
with the octane we run, ping is not really an issue.. As to why the high
mixture and why it would cause ping, I have some ideas, but really, I
don't think it's all that important as long as I have a measuring cup...

That being said in my lawn equipment and boats I run regular fuel with
Spectro32:1 which is designed to run at that mixture in most two stroke
engines.. It's universal.


No it isn't! Water cooled outboards run at much lower temps than air
cooled lawn equipment. The requirements for the oil are quite
different.

And 32:1 will cause an engine that is designed for 50:1 to run lean.
Not good!




It's apparent you don't understand what the ration you used means.

32:1 means 32 parts gasoline to one part oil
50:1 means 50 parts gasoline to one part oil

Therefore, you are wrong to say 32:1 will burn leaner than 50:1. Fifty to one burns leaner by virtue of the fact that there is
more gasoline to burn and less oil.

A richer oil/gasoline ratio (more oil to gas as in 32:1) will cause a two-stroke engine to run richer - not leaner. Oil also
burns (most of it) but oil burns less easily and more slowly (under the compression ratios present in gasoline engines) because
it's less combustible than gasoline. It takes a high compression, diesel engine to burn oil efficiently. It ain't gonna happen
efficiently in a gasoline engine because of the low compression ratios


Wilbur Hubbard

Lots of trimming

Also, I've never seen oil being more subject to explosion/flash than
gasoline. How does adding oil to fuel make it more volatile?

L8R

Skip

There are 2 parameters to consider these are the flash point - the min
temp at which it will ignite with a spark or flame etc.
This is typically -45F for petrol (gasoline) and +143F for diesel.
Hence as a boat fuel, diesel is a lot 'safer' than gasoline.

However there is also the autoignition temperature - this is the min
temp where the fuel will simply ignite without a spark or flame.
For Petrol this is 495F and for diesel 410F a fair bit cooler.

So too much oil could lower the auto ignition temp to a point where
pre-ignition happens - not good for your engine.

However I have no idea how much you need to add to cause this kind of
problem.

You can do a test yourself. Place a drop of gasoline down the barrel of a daisy BB gun and fire it....no effect. Use a drop of oil
and you will hear the detonation when the lube oil detonates. Further, try running a diesel engine on high octane gasoline and see
what doesn't happen. You may be able to move to 50:1 from 100:1.....maybe, but modern two stroke engines use a lot more
compression than the older ones and when using too much oil in the mix, you will melt a piston.
Steve

"Flying Pig" wrote in message ...
"Steve Lusardi" wrote in message ...
Ted,
Adding lube oil to gasoline lowers the flash point of the fuel increasing the chance of detonation. Oil in the fuel is
necessary for these type of engines, but NEVER use more than the manufacturer's recommendation. Failure to follow this simple
direction could melt the pistons, the heads and effectively ruin the engine and I have seen this hundreds of times. I know this
is counter intuitive, hence the number of times this failure occurs.
Steve


Interesting. The Outboard Shop, the local evinrude/johnson dealer, gave me the exact opposite recommendation. The question came
up with my newer engine which is designed to run on 100-1 mix. They told me it will run just fine on the same stuff as my older
engine, a 50-1 mix. They also cautioned me that the least "too-little" mix , such as missing by a bit when filling from a
not-empty supply and having to guess at the right amount, could turn it into an anchor. Failure to use enough deprives the
engine of its lubrication, and things seize up.

Further, my manuals for both engines show to use double the oil in severe use conditions. I.e., in the newer one, 50-1, in the
older one, 25-1. More oil, at least as inferred from the manuals, assures that won't happen, even if you overdo it.

I grant you that quadrupling the oil may have some deletorious effects, but my common sense tells me that 16% more than
specified as ADEQUATE should not be a problem.

Also, I've never seen oil being more subject to explosion/flash than gasoline. How does adding oil to fuel make it more
volatile?

L8R

Skip

--
Morgan 461 #2
SV Flying Pig KI4MPC
See our galleries at www.justpickone.org/skip/gallery!
Follow us at http://groups.google.com/group/flyingpiglog and/or
http://groups.yahoo.com/group/TheFlyingPigLog

"Believe me, my young friend, there is *nothing*-absolutely nothing-half so
much worth doing as simply messing, messing-about-in-boats; messing about in
boats-or *with* boats.
In or out of 'em, it doesn't matter. Nothing seems really to matter, that's
the charm of it.
Whether you get away, or whether you don't; whether you arrive at your
destination or whether you reach somewhere else, or whether you never get
anywhere at all, you're always busy, and you never do anything in
particular; and when you've done it there's always something else to do, and
you can do it if you like, but you'd much better not."

On Mon, 25 Oct 2010 13:13:49 -0400, "Flying Pig"
wrote:

"Steve Lusardi" wrote in message
...
Ted,
Adding lube oil to gasoline lowers the flash point of the fuel increasing
the chance of detonation. Oil in the fuel is necessary for these type of
engines, but NEVER use more than the manufacturer's recommendation.
Failure to follow this simple direction could melt the pistons, the heads
and effectively ruin the engine and I have seen this hundreds of times. I
know this is counter intuitive, hence the number of times this failure
occurs.
Steve


Interesting. The Outboard Shop, the local evinrude/johnson dealer, gave me
the exact opposite recommendation. The question came up with my newer engine
which is designed to run on 100-1 mix. They told me it will run just fine
on the same stuff as my older engine, a 50-1 mix. They also cautioned me
that the least "too-little" mix , such as missing by a bit when filling from
a not-empty supply and having to guess at the right amount, could turn it
into an anchor. Failure to use enough deprives the engine of its
lubrication, and things seize up.

when the evinrude was re-built the mechanic told me to mix 50-1
instead of the regular 25-1 until it got broken in. when i asked
if it would hurt to keep mixing it that way all the time he said
no.

Further, my manuals for both engines show to use double the oil in severe
use conditions. I.e., in the newer one, 50-1, in the older one, 25-1. More
oil, at least as inferred from the manuals, assures that won't happen, even
if you overdo it.

I grant you that quadrupling the oil may have some deletorious effects, but
my common sense tells me that 16% more than specified as ADEQUATE should not
be a problem.

that mechanic and the jetski mechanic both said too much is okay
but too little will ruin the engine because what you're doing is
running it low on oil, which certainly makes sense.

Also, I've never seen oil being more subject to explosion/flash than
gasoline. How does adding oil to fuel make it more volatile?

for real. i've been running the evinrude about 50-1 for about a
year and it hasn't blown up or even overheated. one person told
me that mixing too much oil makes it have a problem with wanting
to quit when you're trying to start it...it will fire up for a
few seconds and then die which it is doing. but he may have just
said that because he knew i was mixing it heavy on oil. he told
me that at a time when we were having the problem. it usually
only does it once or twice though, and then runs fine.

Interesting that my comments should have had the group ranting and raving.

Nice, however, to see WH/GH ack their duality, finally, after all the "he's
my roommate" and the like denials.

Meanwhile, inquiring minds still want to know...

Why do outboard manufacturers insist that you run double the oil during
breakin, and under severe operating conditions, if it's likely to blow out
the pistons as liquid aluminum?

Never mind whether or not a certified mechanic can be trusted or whether or
not I selectively read. At least one poster has verified doubling the oil
during breakin so it stands to reason that it MIGHT be possible that the
manual actually says the same about severe operating conditions...

L8R

Skip, chasing his starting issues, still, report to follow

--
Morgan 461 #2
SV Flying Pig KI4MPC
See our galleries at www.justpickone.org/skip/gallery!
Follow us at http://groups.google.com/group/flyingpiglog and/or
http://groups.yahoo.com/group/TheFlyingPigLog

"Believe me, my young friend, there is *nothing*-absolutely nothing-half so
much worth doing as simply messing, messing-about-in-boats; messing about in
boats-or *with* boats.
In or out of 'em, it doesn't matter. Nothing seems really to matter, that's
the charm of it.
Whether you get away, or whether you don't; whether you arrive at your
destination or whether you reach somewhere else, or whether you never get
anywhere at all, you're always busy, and you never do anything in
particular; and when you've done it there's always something else to do, and
you can do it if you like, but you'd much better not."

On Tue, 26 Oct 2010 16:54:44 -0400, "Flying Pig"
wrote:

Never mind whether or not a certified mechanic can be trusted or whether or
not I selectively read. At least one poster has verified doubling the oil
during breakin so it stands to reason that it MIGHT be possible that the
manual actually says the same about severe operating conditions...

I don't think so. That's when you're likely to experience
pre-ignition/detonation due to the lowered self ignition temperature
of the fuel mix.

"Wayne.B" wrote in message
...
On Tue, 26 Oct 2010 16:54:44 -0400, "Flying Pig"
wrote:

Never mind whether or not a certified mechanic can be trusted or whether
or
not I selectively read. At least one poster has verified doubling the oil
during breakin so it stands to reason that it MIGHT be possible that the
manual actually says the same about severe operating conditions...

I don't think so. That's when you're likely to experience
pre-ignition/detonation due to the lowered self ignition temperature
of the fuel mix.




Duh! Increasing the oil to fuel ratio does not lower the self-ignition
temperature. It raises it. We are not talking diesel engines here. We are
talking two-stroke gasoline engines with their relatively low compression
ratios.

Try running a two-stroke (two-cycle) engine on pure two-stroke oil and they
won't self ignite to combustion EVER! Even a spark plug won't make the thing
fire.

Try running them on half and half gas and oil and they might just barely run
given a source of ignition like a spark plug before it fouls with oil in
about a minute but they won't self-ignite EVER.

Try running them on nothing but gasoline and they will have a much higher
likelihood of self-ignition (aka detonation, knock or ping) for about a
minute before the piston seizes to the cylinder wall.

I hate like hell to say it but SKIPPY IS CORRECT. Increasing the oil to fuel
ratio will not damage the engine from detonation, etc.


Wilbur Hubbard

From Page 8 of the OMC manual for the 15HP, a 1992j model:

To protect your new outboard motor during the intiial hours of operation,
and to seat internal engine components, you MUST (emphasis theirs) add extra
oil during the break-in period.

The fuel/oil ratio for the first 12 gallons must be *25-1* (emphasis
theirs).

The fuel oil ratio during normal operation, after break-in, must be *50-1*
(emphasis theirs).


My 6HP manual in hand is just before they went to 100-1 oil. Note that
this, a 2005 manual, as the dealer didn't have a current one, is for the
normally 50-1 mix engine. My 6 is actually a couple of years later, and the
recommended use is for half of that shown above. As mine was a trade-in, it
didn't happen to have its original manual, explaining why I'm looking at an
older one.

It says, on page 15:

The fuel/oil ratio for the first 10 hours must be *25-1* (emphasis theirs).

The fuel oil ratio during normal operation, after break-in, must be *50-1*
(emphasis theirs).

HOWEVER...

"During high performance opertion you must use a *25-1* fuel/oil ratio in
your fuel tank."

Now, I agree, OMC is a poor source of information about what to use in their
engines for them to warranty them.

But until some more authoratative source presents, I'm going with the
manual.l NOTHING in it suggests, and, quite the contrary, demands its use,
for high performance, that doubling the oil is harmful to the engine.

Indeed, high performance seems to me to be more stressful, and, as such, if
the assertions that too much oil will melt the aluminum, that the
recommendation would be for LESS oil, not doubling it...

L8R

Skip

--
Morgan 461 #2
SV Flying Pig KI4MPC
See our galleries at www.justpickone.org/skip/gallery!
Follow us at http://groups.google.com/group/flyingpiglog and/or
http://groups.yahoo.com/group/TheFlyingPigLog

"Believe me, my young friend, there is *nothing*-absolutely nothing-half so
much worth doing as simply messing, messing-about-in-boats; messing about in
boats-or *with* boats.
In or out of 'em, it doesn't matter. Nothing seems really to matter, that's
the charm of it.
Whether you get away, or whether you don't; whether you arrive at your
destination or whether you reach somewhere else, or whether you never get
anywhere at all, you're always busy, and you never do anything in
particular; and when you've done it there's always something else to do, and
you can do it if you like, but you'd much better not."

On Mon, 25 Oct 2010 18:48:09 +0200, "Steve Lusardi"
wrote:

Ted,
Adding lube oil to gasoline lowers the flash point of the fuel increasing the chance of detonation. Oil in the fuel is necessary
for these type of engines, but NEVER use more than the manufacturer's recommendation. Failure to follow this simple direction
could melt the pistons, the heads and effectively ruin the engine and I have seen this hundreds of times.

as yet i find it hard to believe that you've seen it happen at
all, much less hundreds of times. how much more oil are you
talking about?

I know this is counter intuitive,

to say the least.

hence the number of times this failure occurs.

can you provide any reason to believe that happens a lot, other
than your own unlikely sounding claim? i've never heard of it
happening at all, and if it were as common as you say it is it
seems it's one of those things mechanics would warn people about.

ted@theted. wrote in message ...
i have a jetski and a boat with an evinrude 115 hp outboard. can
they both use the same gas/oil mix? someone told me it should be
a pint to six gallons but i would rather mix a pint with 5
gallons because it's easier and to be on the safe side if that's
ok. is a pint to 5 gallons ok for both the jetski and the
evinrude?

thanks!

ted

On Oct 25, 12:02*pm, ted@theted. wrote:
i have a jetski and a boat with an evinrude 115 hp outboard. can
they both use the same gas/oil mix? someone told me it should be
a pint to six gallons but i would rather mix a pint with 5
gallons because it's easier and to be on the safe side if that's
ok. is a pint to 5 gallons ok for both the jetski and the
evinrude?

thanks!

ted

I only have smaller 2 strokes and one jetski. The jetski mixes it's
self with a oil pump to the carbs. But I mix the same ratio for all
my small engines without any problems.