Not so sure. Gasoline flashes fairly low. But oil has lower octane than
any gas. So pinking or detonation could still be an issue, no doubt.
That's if the compression still makes it up there.....

Brian W

Steve Lusardi wrote:
50 to 1 Remember, too much oil will reduce the flash point of the fuel and
create detonation, which will melt piston and head.
Steve

"rckchp" wrote in message
...
OT. I'm reactivating a 1997 Evinrude 9.9 hp outboard and I've
misplaced the owner manual, and I don't remember the proper oil mix
ratio. Is it 50 to 1, or 100 to 1? Thanks.

On Sun, 14 Jun 2009 13:03:58 -0500, Brian Whatcott
wrote:

Not so sure. Gasoline flashes fairly low. But oil has lower octane than
any gas. So pinking or detonation could still be an issue, no doubt.
That's if the compression still makes it up there.....

Brian W


It will certainly cause excessive carbon buildup, which will
eventually seize or break the rings, and cause other damage and
runnability issues.



Steve Lusardi wrote:
50 to 1 Remember, too much oil will reduce the flash point of the fuel and
create detonation, which will melt piston and head.
Steve

"rckchp" wrote in message
...
OT. I'm reactivating a 1997 Evinrude 9.9 hp outboard and I've
misplaced the owner manual, and I don't remember the proper oil mix
ratio. Is it 50 to 1, or 100 to 1? Thanks.

On Sun, 14 Jun 2009 13:03:58 -0500, Brian Whatcott
wrote:

Not so sure. Gasoline flashes fairly low. But oil has lower octane than
any gas. So pinking or detonation could still be an issue, no doubt.
That's if the compression still makes it up there.....

Brian W

Steve Lusardi wrote:
50 to 1 Remember, too much oil will reduce the flash point of the fuel and
create detonation, which will melt piston and head.
Steve

"rckchp" wrote in message
...
OT. I'm reactivating a 1997 Evinrude 9.9 hp outboard and I've
misplaced the owner manual, and I don't remember the proper oil mix
ratio. Is it 50 to 1, or 100 to 1? Thanks.

Flash point has nothing to do with detonation which is controlled by
octane rating and compression.

Flash point is the temperature at which vapors ignite and since
kerosene (with its higher flash point) will burn in most internal
combustion engines it seems that flash point is of only minor
interest.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Bruce,
You are a nice guy, but you are not correct here. Please pay close
attention, heavy lube oil contamination will create detonation in spark
ignition engines. It will melt pistons, spark plugs and heads, especially in
outboard motors. The percentage of oil in the fuel that creates this damage
is a matter of heat.The higher the heat of the combustion chamber, the lower
the oil percentage threshold that diesels the fuel mix . The reason this is
more dangerous in outboards is because the noise of detonation is muffled by
the water jacket and masked by excess ambient noise in the boat.
Additionally the severity of this condition is greatly amplified by throttle
position and the general mode of operation is WOT. If you think for one
second that flash point of fuel is not significant, place a drop of gasoline
down the barrel of a daisy BB gun and fire it. No change. Place of drop of
oil in the barrel and repeat the test. It easily detonates when the spring
is released. I used to this all the time as a kid.
Steve

"Bruce In Bangkok" wrote in message
...
On Sun, 14 Jun 2009 13:03:58 -0500, Brian Whatcott
wrote:

Not so sure. Gasoline flashes fairly low. But oil has lower octane than
any gas. So pinking or detonation could still be an issue, no doubt.
That's if the compression still makes it up there.....

Brian W

Steve Lusardi wrote:
50 to 1 Remember, too much oil will reduce the flash point of the fuel
and
create detonation, which will melt piston and head.
Steve

"rckchp" wrote in message
...
OT. I'm reactivating a 1997 Evinrude 9.9 hp outboard and I've
misplaced the owner manual, and I don't remember the proper oil mix
ratio. Is it 50 to 1, or 100 to 1? Thanks.

Flash point has nothing to do with detonation which is controlled by
octane rating and compression.

Flash point is the temperature at which vapors ignite and since
kerosene (with its higher flash point) will burn in most internal
combustion engines it seems that flash point is of only minor
interest.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

On Fri, 3 Jul 2009 19:11:24 +0200, "Steve Lusardi"
wrote:

Bruce,
You are a nice guy, but you are not correct here. Please pay close
attention, heavy lube oil contamination will create detonation in spark
ignition engines. It will melt pistons, spark plugs and heads, especially in
outboard motors. The percentage of oil in the fuel that creates this damage
is a matter of heat.The higher the heat of the combustion chamber, the lower
the oil percentage threshold that diesels the fuel mix . The reason this is
more dangerous in outboards is because the noise of detonation is muffled by
the water jacket and masked by excess ambient noise in the boat.
Additionally the severity of this condition is greatly amplified by throttle
position and the general mode of operation is WOT. If you think for one
second that flash point of fuel is not significant, place a drop of gasoline
down the barrel of a daisy BB gun and fire it. No change. Place of drop of
oil in the barrel and repeat the test. It easily detonates when the spring
is released. I used to this all the time as a kid.
Steve

I suspect that you are correct when you use the words "heavy lube oil
contamination will create detonation" however whether this is a factor
in outboard motors in normal use is questionable. In the old days
outboard used gas oil mixes of 10::1 with no apparent damage. Then
mixes went to the 20 - 25::1 range and more recently to the 50::1
range.

While I do not doubt that there is some level of oil mix that will
cause detonation but I doubt very strongly that it is a factor in
actual use given that oil mixes were, in the early days, recommended
that were 3 times richer then today's rather anemic mixtures.

In addition premixed gasoline is used in chain saws, motorcycles, weed
whackers, small generators, lawn mowers and even model airplanes. All
without noticeable detonation problems.

Another point is that I have seen 4 stroke engines that used so much
oil that the spark plugs fouled within hours of use, but were not
damaged by detonation. Most 2-stroke outboard engines, on the other
hand, do not contaminate their plugs in months/years of use.

While I would not argue with your assertion I do not believe that
"heavy lube oil contamination of the fuel" is ever going to be a
problem in even poorly serviced outboard engines to a degree necessary
to produce detonation.


"Bruce In Bangkok" wrote in message
.. .
On Sun, 14 Jun 2009 13:03:58 -0500, Brian Whatcott
wrote:

Not so sure. Gasoline flashes fairly low. But oil has lower octane than
any gas. So pinking or detonation could still be an issue, no doubt.
That's if the compression still makes it up there.....

Brian W

Steve Lusardi wrote:
50 to 1 Remember, too much oil will reduce the flash point of the fuel
and
create detonation, which will melt piston and head.
Steve

"rckchp" wrote in message
...
OT. I'm reactivating a 1997 Evinrude 9.9 hp outboard and I've
misplaced the owner manual, and I don't remember the proper oil mix
ratio. Is it 50 to 1, or 100 to 1? Thanks.

Flash point has nothing to do with detonation which is controlled by
octane rating and compression.

Flash point is the temperature at which vapors ignite and since
kerosene (with its higher flash point) will burn in most internal
combustion engines it seems that flash point is of only minor
interest.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Years ago when Evinrude and Mercury were promoting the V4 and their swirl
scavenged 3 and 6 cyl motors, I made a fortune rebuilding these engines for
the USMC, which all suffered from Marines using too much oil in the fuel. I
have also fried Corvette small block motors which suffered intake manifold
leaks on the bottom port surfaces sucking oil vapor from the lifter valley,
as well as Opel fours that lost oil control rings on the German Autobahn. At
partial throttle slight power loss and some pinging results. At full
throttle, parts melt..
Steve

"Bruce In Bangkok" wrote in message
...
On Fri, 3 Jul 2009 19:11:24 +0200, "Steve Lusardi"
wrote:

Bruce,
You are a nice guy, but you are not correct here. Please pay close
attention, heavy lube oil contamination will create detonation in spark
ignition engines. It will melt pistons, spark plugs and heads, especially
in
outboard motors. The percentage of oil in the fuel that creates this
damage
is a matter of heat.The higher the heat of the combustion chamber, the
lower
the oil percentage threshold that diesels the fuel mix . The reason this
is
more dangerous in outboards is because the noise of detonation is muffled
by
the water jacket and masked by excess ambient noise in the boat.
Additionally the severity of this condition is greatly amplified by
throttle
position and the general mode of operation is WOT. If you think for one
second that flash point of fuel is not significant, place a drop of
gasoline
down the barrel of a daisy BB gun and fire it. No change. Place of drop of
oil in the barrel and repeat the test. It easily detonates when the spring
is released. I used to this all the time as a kid.
Steve

I suspect that you are correct when you use the words "heavy lube oil
contamination will create detonation" however whether this is a factor
in outboard motors in normal use is questionable. In the old days
outboard used gas oil mixes of 10::1 with no apparent damage. Then
mixes went to the 20 - 25::1 range and more recently to the 50::1
range.

While I do not doubt that there is some level of oil mix that will
cause detonation but I doubt very strongly that it is a factor in
actual use given that oil mixes were, in the early days, recommended
that were 3 times richer then today's rather anemic mixtures.

In addition premixed gasoline is used in chain saws, motorcycles, weed
whackers, small generators, lawn mowers and even model airplanes. All
without noticeable detonation problems.

Another point is that I have seen 4 stroke engines that used so much
oil that the spark plugs fouled within hours of use, but were not
damaged by detonation. Most 2-stroke outboard engines, on the other
hand, do not contaminate their plugs in months/years of use.

While I would not argue with your assertion I do not believe that
"heavy lube oil contamination of the fuel" is ever going to be a
problem in even poorly serviced outboard engines to a degree necessary
to produce detonation.


"Bruce In Bangkok" wrote in message
. ..
On Sun, 14 Jun 2009 13:03:58 -0500, Brian Whatcott
wrote:

Not so sure. Gasoline flashes fairly low. But oil has lower octane than
any gas. So pinking or detonation could still be an issue, no doubt.
That's if the compression still makes it up there.....

Brian W

Steve Lusardi wrote:
50 to 1 Remember, too much oil will reduce the flash point of the fuel
and
create detonation, which will melt piston and head.
Steve

"rckchp" wrote in message
...
OT. I'm reactivating a 1997 Evinrude 9.9 hp outboard and I've
misplaced the owner manual, and I don't remember the proper oil mix
ratio. Is it 50 to 1, or 100 to 1? Thanks.

Flash point has nothing to do with detonation which is controlled by
octane rating and compression.

Flash point is the temperature at which vapors ignite and since
kerosene (with its higher flash point) will burn in most internal
combustion engines it seems that flash point is of only minor
interest.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

On Sat, 4 Jul 2009 22:00:05 +0200, "Steve Lusardi"
wrote:

Years ago when Evinrude and Mercury were promoting the V4 and their swirl
scavenged 3 and 6 cyl motors, I made a fortune rebuilding these engines for
the USMC, which all suffered from Marines using too much oil in the fuel. I
have also fried Corvette small block motors which suffered intake manifold
leaks on the bottom port surfaces sucking oil vapor from the lifter valley,
as well as Opel fours that lost oil control rings on the German Autobahn. At
partial throttle slight power loss and some pinging results. At full
throttle, parts melt..
Steve

How about some definitive numbers here. You say that the engines were
failing due to excessive oil in the premix - how much was too much?

Your experience seems very much at odds with my own as we had a slue
of Mercury six cylinder inline engines, in Iran Jaya, that were
seizing and the solution prior to my taking over as marine maintenance
was to add oil and add oil and add oil.
(the actual cause was weak fuel pumps which caused the top carb to run
lean).

I've seen detroit diesels "run away" and literally run on lube oil
from failed blower seals with no detonation problems. If too much oil
causes detonation then these engines certainly should have detonated
as they were running on straight lube oil.

Another problem I have with your assertion is that extra heavy oil
mixes - double the amount of oil, or more - usually resulted in the
engines running cooler then normal due to very poor combustion of the
high oil content mixes.

The small block chevies I've seen suck oil from the intake manifold
all ran with less power and smoked a lot but with no damage to pistons
from detonation.

In fact the only detonation damage I have ever seen was always traced
back to a lean mixture or too high supercharger pressure for the RPM.

By the way, in the early days of Yamaha racing the road racers had
problems with the engines seizing when you rolled the throttle back at
the end of a long straight. High engine temperature from the long full
throttle run combined with a sudden reduction in lube oil from the
closed throttle valve. (It made the drivers rather unhappy when the
rear wheel stopped turning at over 100 MPH). The immediate solution
was "ADD OIL" to the premix. It didn't cause detonation.

Even model airplane engines would sometime detonate - always from a
lean mixture.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Bruce,
Lets define detonation first, just so we are both on the same sheet of
music. Detonation is the collision of two simultaneous spreading flame
fronts sweeping across the combustion chamber. When the two flame fronts
collide, the remaining fuel burns at an explosive rate causing both a very
rapid rise in cylinder pressure and temperature. Under normal operation the
fuel/ air charge ignites from a single point in the squish area of the
combustion chamber and ignition propagates at a controlled rate so that all
the fuel is burning before the piston starts its downward travel. This is
timed so that the maximum cylinder pressure achieved from the burn occurs at
the most advantageous crankshaft angle. The start of the ignition cycle is
supposed to be controlled by spark timing on gasoline engines and injector
timing on diesels. The extent of the damage caused by this phenomena is a
product of the remaining fuel yet unburned at the time of the collision. You
are correct when you stated that detonation can be observed in many other
engine types. In point of fact, it can also occur in firearms. All fuels are
designed to burn at a controlled rate and temperature, but when those
parameters are exceeded, the burn characteristics of the fuel change.

I disagree with your statement that your experiences are at odds with mine.
I don't think they are. Your experience in Iran as the first example, I
suggest, was not detonation, it was overheating caused by the lean
condition. This violated the stoichiometric ratio of fuel and air that
gasoline is designed to burn within and the burn temperature rose to
abnormal levels overheating the piston causing thermal expansion beyond the
available space for this (piston/cylinder clearance), hence the seizure.
This is also the case in racing two stroke motorcycles. In the old days lube
oil was added to the fuel at fueling time, which made the fuel air ratio
important for lubrication as well as burn parameters. On all later model
high performance two stroke engines, a separate oil pump was employed that
metered oil into the air fuel stream from a separate oil tank eliminating
this fuel/oil dependency. It may be necessary to state that lean is mean.
All internal combustion engines are really hot air engines and it is the
displacement difference of the ingested air at atmospheric temperatures
verses the same air heated by fuel combustion that drives the piston
downward, not the exhaust gases of the fuel burned. So, it stands to reason
that the more heat generated during the ignition cycle, the greater the
cylinder pressure achieved. Maximum heat is generated in the leaner side of
stoichiometric, so it can be a fine line between max power and disaster.
Now, I am not saying detonation did not occur, I was not there, but if it
did occur, it was a secondary effect, not primary and in point of fact, the
addition of excessive oil in the fuel aggravated the condition.

In the case of Detroit Diesel engines (DDA), yes, they very happily will run
on their own lube oil, but that is not detonation it is simply compression
ignition, as the self ignition temperature of lube oil and diesel fuel is
similar. This fact supports my original statement that the addition of lube
oil causes detonation in gasoline engines, because gasoline self ignites at
a higher temperature than lube oil. Please recall the big warning sign in
the cabs of the military trucks with multi fuel engines stating not to use
high octane gasoline. This is because the compression temperature rise in
not sufficient to ignite that fuel.

Please note that I have avoided the causes of detonation because there are
many. This discussion is only about the presence of lube oil in gasoline and
there is a limit of tolerance before the compression ignition of the oil
takes place prior to the occurrence of the spark. This causes pinging which
is normally heard by the operator, but if this warning is ignored and wide
open throttle (WOT) is used, you can expect melted parts.
Steve