Fogging oil

thumpar

Admiral
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Jun 21, 2007
Messages
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I have some of the stabil labeled fogging oil from when I used to use it. It works like the others.
 

JoLin

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Aug 18, 2007
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I fill a new fuel water separator halfway with Marvel Mystery Oil. Start the motor, then pour more down the carb throat until the motor stumbles hard (it doesn't usually die). Yell 'cut it!" up to the bridge, where a helper shuts off the key. My motors are carbed, so no sensors to potentially screw up. A quart of MM oil costs $4.00 and fogs 2 motors. No problems in the Spring aside from a big cloud of smoke when they start the first time.

Unnecessary? Maybe, but my boat is laid up for 6-7 months a year. It's cheap and makes me feel better.

My .02
 

dingbat

Supreme Mariner
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Nov 20, 2001
Messages
15,414
Gee, fogging oil is introduced into a motor to keep the rust down. Some folks have cited that 4 cycle motors don't need fogging. I have the opposite opinion, since 4 cycle motors run straight gas. I think they need more fogging than 2 cycle motors. Also, sterndrive motors have a lot more cast iron parts than outboard motors. Since iron rusts, I would think fogging would be mandatory at least for sterndrives.

Cast iron absorbs oil like a sponge. I have a spare jug for my golf cart under my work bench that was taken out of service 3-4 years ago. The outside fins are starting to show some rust but not the bore. Far too impregnated with oil from it's years of service to rust.

I fogged my 4 stroke Merc Cruiser back in the day. Since moving over to OB, I use the simple "choke to stall" procedure the last time out for the year, if I remember.

For me, it doesn't matter one way or another. Winter is 3 months at best.
 

frantically relaxing

Senior Chief Petty Officer
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Nov 19, 2011
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Seafoam-- Yes, by all means, DO fog your engine with it. It's stupendous at loosening carbon on the valves and pistons. Pour it slowly and keep the engine running. Just beware the huge white cloud of smoke...

But DO NOT fog it and then kill the motor for winter, that's not what it's for. When done, let the motor run a couple more minutes to clear the residual Seafoam and guck out. Then call it a day, or fog with oil if that's your prerogative... :)
 

JimS123

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Jul 27, 2007
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I have outboards from 1955, 1968, 1970 and 1984. All were bought new and I have the original owner's manuals for each. ALL the manuals say to fog for winter storage. ALL have been done annually and all still run and run well.

I also have a 1919 Evinrude Rowboat motor and a reprint of the manual. That also says to fog for winter with motor oil (they didn't have a specific fogging oil back then).

Maybe the motor manufacturers just want to sell oil. They sure don't know as much as the average boater. In any event, how many 1955 motors do you still see running around? The fogging oil costs 7 cents and fogging takes 32 seconds. So what's the big deal?
 

H20Rat

Vice Admiral
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Mar 8, 2009
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5,199
For the 10 minutes it takes to fog the carbs and the cheap price of fogging oil compared to the cost of running her I do exactly as he suggested. 21 year old motors start first or second turn of the keys, every time. No carb work since I have had her.

No need to fog a 4 stroke especially with fuel injection. It won't hurt anything though. And no more Seafoam to fog right?

It has apparently worked for you so keep doing it, but you aren't fogging the carbs. You are just spraying through the big giant air passages on the carbs. The part of a carb that will plug up are the fuel passageways, which fogging has absolutely zero affect on. The purpose of fogging is presumably to coat the inside of the cylinder with oil to prevent rust.

Also, fogging on a EFI engine can ABSOLUTELY hurt things... Spray a bunch of fogging oil the MAF sensor and you will have a couple hundred dollar repair next season. Delicate temperature/pressure/flow sensors don't take kindly to being hosed down with oil.
 

Comogene

Cadet
Joined
Mar 5, 2006
Messages
29
It is a matter of choice and makes me feel comfortable. I have always fogged my carbed inboards. Mix 1 quart of Rislone, Mystery Oil or 2-stroke oil (even transmission fluid) with equal part gasoline. Break the fuel line and insert line into the mixture. Run engine at fast idle until it stalls. Over the winter 5-6 months, the gas evaporates and leaves the oil residue coating throughout the carb, intake and cylinders. To do two 454s and a generator takes 15 minutes or so and less than $10 in supplies. In the spring, fill the Racors with fresh gas, clean or replace spark plugs and wipe out the mosquito population when restarting. As noted, spraying fogging oil into the cylinders leaves the carb unprotected.

I winter in salt water so there is always the issue of moisture seeping in through the exhaust system to the valves. The fogging process hopefully, inhibits the rusting.

Gene
 

JimS123

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Also, fogging on a EFI engine can ABSOLUTELY hurt things... Spray a bunch of fogging oil the MAF sensor and you will have a couple hundred dollar repair next season. Delicate temperature/pressure/flow sensors don't take kindly to being hosed down with oil.

In that case, maybe the owner's manual details what winterizing is required.
 

thumpar

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Jun 21, 2007
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In that case, maybe the owner's manual details what winterizing is required.
I know the service manual covers it. One mine with the VST you are supposed to use 2 cycle oil straight into the VST and run it with fuel shut off to pump until the VST is empty. For cool fuel you put the 2 cycle oil into the fuel/water separator and run it.
 

crazy charlie

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May 22, 2003
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[QUOTE. Do guys with classic cars bother fogging the engine when they park them for the winter? I don't think they do. [/QUOTE]
WE SURE DO !!! We call it" pickling "the motor. It is only necessary if you want to assure yourself that you are protecting the internals of your motor to the best of your ability at minimum effort.I would 100% recommend fogging marine engines.Depending on where you store the boat ,the changes in daily air temps will actually make your motor sweat /condensate all over the outside .....imagine whats going on inside.Motors work best and last longest when the are run.When a motor sits w/o running all kinds of negative affects begin to take place.Think of fogging your motor as putting it in "suspended animation". It is a guarantee that the motors inside will be exactly the same months later as when you last used it.That is the simplist way I can describe it.Charlie
 

camalot

Petty Officer 2nd Class
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Jul 24, 2012
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144
I would say it depends where you live IMO. We fog everything...living right on the Atlantic coast in canada it's quite a harsh environment to be idle for 7/8 months. In a warmer dryer winter I'd say na don't bother.
 

camalot

Petty Officer 2nd Class
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Jul 24, 2012
Messages
144
Well, waddayano, Stabil makes fogging oil! Whoda thunk?
Of course they claim you should use it in two- and four- stroke engines. Well, actually they say motor, but we all know that's not correct.
Here's the thing - back in the early 90's, when I lived in Hawaii, I used fogging oil in all my two stroke motorcycle engines whenever they went into storage for six months or more; the cans even specified two-stroke use. The logic at the time was that the combustion chamber got its lubrication from oil that was burned along with the gasoline and parts (such as reed valves) needed to be protected from corrosion. Fogging oil coated everything nicely and kept everything lubricated. When I moved to Texas in 1994, nobody I talked to ever even heard of fogging oil. I went on deployments without fogging my engines. Oddly enough, they all survived just fine. Now, years later, fogging oil is on all the shelves and it is designed to be used in all engines.
The upshot is, if you like it, using it makes you feel better, and you aren't starving your kids to pay for it. I say use it if you want. As for me, I'm filing it under snake-oil.
Two strokes are a little different than a 4 stroke as there will always be a cylinder open to the environment through a exhaust port, if that piston is low enough in the cylinder then the cases and crank bearing will be exposed to the environment by the transfer ports. In Texas I would totally agree with you it's snake oil and unneeded, but in higher humid places IMO it's a must.
 

Lou C

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Nov 10, 2002
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11,798
This really depends on your climate when the boat is stored. If you are in a very dry climate like the arid Southwest then it may no be necessary. But here in the North East with the temperature swings and humidity in the winter it is highly advised. When you store your boat take a look at the engine if you can, after a night where the weather went from fairly warm to much cooler at night. In the morning there will be condensed moisture dripping off the engine and this goes on inside via an open exhaust valve too. I always fogged the boat but not the 2 cycle yard engines because they are stored inside in a much dryer environment.
 

HT32BSX115

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Dec 8, 2005
Messages
10,083
Also, sterndrive motors have a lot more cast iron parts than outboard motors. Since iron rusts, I would think fogging would be mandatory at least for sterndrives.

I wanted to keep the rust down in the intake manifold, as I did not want to replace it. My assumption was that some of the 2 cycle oil would end up on the inside of the intake manifold and keep the cast iron from rusting.
Maybe, but the rust will occur in the water jacket area of the intake manifold MUCH quicker than inside the intake area where there's little or no water inside. Fogging will not help you there.
I winter in salt water so there is always the issue of moisture seeping in through the exhaust system to the valves. The fogging process hopefully, inhibits the rusting.
If you get salt water "seeping" into the exhaust (presumably from a leaking riser gasket) , NO amount of fogging will save you! The engine will be junk by Spring.

Unnecessary? Maybe, but my boat is laid up for 6-7 months a year. It's cheap and makes me feel better.
Mine sits from AUG-JUN. I don't fog and I feel just fine. My last boat was only 39 years old (head never off the 150 Mercruiser) when I sold it. It never was fogged from since new.

The upshot is, if you like it, using it makes you feel better, and you aren't starving your kids to pay for it. I say use it if you want. As for me, I'm filing it under snake-oil.
:facepalm:Yeah. Me too!:thumb:
 

muc

"Retired" Association of Marine Technicians...
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Jul 7, 2004
Messages
2,064
It has apparently worked for you so keep doing it, but you aren't fogging the carbs. You are just spraying through the big giant air passages on the carbs. The part of a carb that will plug up are the fuel passageways, which fogging has absolutely zero affect on. The purpose of fogging is presumably to coat the inside of the cylinder with oil to prevent rust.

Also, fogging on a EFI engine can ABSOLUTELY hurt things... Spray a bunch of fogging oil the MAF sensor and you will have a couple hundred dollar repair next season. Delicate temperature/pressure/flow sensors don't take kindly to being hosed down with oil.

smokingcrater I have never seen an I/O with a mass air flow sensor. What motors have you seen them on?

I have torn down more than a few I/O motors for repairs in the winter and there is a lot less rust in the cylinders and on the valves when they were fogged.
But I'm in Minnesota and I do believe that climate makes a big difference.
 

boobie

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Nov 5, 2009
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20,826
I've used Dextron ATF for fogging oil for a number of years and had good luck with it. JMO
 

Jeepster04

Chief Petty Officer
Joined
Jan 5, 2009
Messages
481
I've always fogged our engines and Ive never had any issues. The stuff is only $3 a can and it takes literally 1 minute to fog them.

One of our boats stays in the water year around and has 3 engines on it. Like someone mentioned, the blocks will be dripping with water if the air temperature warms up quick enough and the temperature of the blocks lag behind. Its nice knowing the inside of the engine is coated with oil while this is happening ALL winter long.

I spray down each bore a few times then close the choke. Some of the engines are beasts to get started come spring from the fouled plugs but those engines are always a little tough to start after they sit for a bit.
 
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