Anti Foam additive in small engine oil

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The question comes up pretty regularly (duh!) about using regular auto oil in small engines. The only real question I've ever had about it is the manufacturers all make a big point of saying small engine oils, (that they sell) have anti foaming additives that keep the oil from aerating. I don't know the chemistry of anti foam agents for oil, but was wondering if anyone had any knowledge on this.
Do all oils have anti foam adds? Are HDEO's better in this respect? Most of my OPE engines are water cooled, with oil pumps, full pressure lubrication and filters, so they can use car oil just fine, but what about an air cooled, oil slinger, that would froth up the oil pretty well?
 

MolaKule

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When any fluid has turbulence associated with it, bubbles form and oil is no exception. Bubbles of course are entrapped gasses and provide no lubrication.

All engine oils of every flavor have foam reducers, which by the way, is what they really are.

Foam inhibitors do not 'inhibit' or stop foam, but they simply cause the bubbles to burst sooner by reducing the surface tension of the bubble.

Labelling hype comes in many flavors as well.
 
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I believe every US and European engine oil spec has a foam limitation written into it. That being said, most every oil will have an anti-foam additive of some sort in it. There are a couple different types, but they are typically chosen for the particular spec they are formulated for.

If the manufacturer is specifically claiming to have formulated for the extra foaming potential in your application, I would tend to take their word for it. If they are saying it is formulated to keep the oil from aerating, then it might not contain any more than a typical engine oil.
 
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When any fluid has turbulence associated with it, bubbles form and oil is no exception. Bubbles of course are entrapped gasses and provide no lubrication.

All engine oils of every flavor have foam reducers, which by the way, is what they really are.

Foam inhibitors do not 'inhibit' or stop foam, but they simply cause the bubbles to burst sooner by reducing the surface tension of the bubble.

Labelling hype comes in many flavors as well
Do motorcycle oils have more anti foam properties than pcmo?
 
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I've never used an
The question comes up pretty regularly (duh!) about using regular auto oil in small engines. The only real question I've ever had about it is the manufacturers all make a big point of saying small engine oils, (that they sell) have anti foaming additives that keep the oil from aerating. I don't know the chemistry of anti foam agents for oil, but was wondering if anyone had any knowledge on this.
Do all oils have anti foam adds? Are HDEO's better in this respect? Most of my OPE engines are water cooled, with oil pumps, full pressure lubrication and filters, so they can use car oil just fine, but what about an air cooled, oil slinger, that would froth up the oil pretty well?
ounce of small engine oil in my life... I have used Mobil 1 for years and most recently Super Tech in all my 4 stroke OPE. I have a 17 Y/O snowblower and 11 Y/O push mower that both run like a top... IMO, I think fuel quality, air filter and oil changes are more important than oil type.

BTW over filling and under filling can be a contributing cause of foaming or aeration of your oil.

Just my $0.02
 
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Do motorcycle oils have more anti foam properties than pcmo?
The JASO motorcycle engine oil specs for foaming tendencies either matched or are less stringent than than the API's for PCMO since API SL.

Sequence I: 10/0
Sequence II: 50/0
Sequence III: 10/0

So although a motorcycle engine oil might have more depending on the manufacturer's formulation, there hasn't been a requirement to boost that performance above the typical PCMO's capability with regards to the performance specifications.

Edit: For additional info; when I was formulating and testing motorcycle engine oils, I don't recall any formulas, experimental or otherwise, ever even coming close to those limits above. I think a lot of them were like 0/0, 5/0, 0/0 or some low foam results like that. I don't really recall any issues with foaming from the field either that couldn't be explained by some extenuating circumstance like excessive contamination or such.
 
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@High Performance Lubricants - can you comment on anti-foam in your oils?
Mola is on the money as usual. There are many types of defoamers with the most common being silicone or methacrylate based. It is probably easier to make some statements that are general with respect to foam. Defoamers have a window of which they work in. More is not necessarily better. In fact if you treat a product with too much defoamer it will actually cause foam that would be much worse than you were originally dealing with. High treat rates of defoamers while reducing foam can actually have a negative effect on air release. Defoamers are very surface active and will cling to surfaces that will deplete their concentration in the oil. Defoamers will be depleted by things like changing filters but not the oil, or transferring from drums to other containers for example. As mentioned above the API allows 50 mils of foam and additionally allows 10 minutes for the foam to break. This is a very loose specification. Our oils will go from a trace of foam to zero in seconds.

We do not treat products any differently based on intended use. We simply ship products that don't foam. Below are some pictures. First of the equipment we use to test for foam. We have 4 testing stations and one dedicated to measuring the cracking pressure and flow rate of the stones used to distribute air into the oil during the foam test. The test is open loop feeding a given amount of air to the stones so the stones must function within a window to be valid. When the stones function outside of this window we will spend $300 on a new one that does. We have invested nearly $100,000 in foam testing equipment. Each foam station has a camera which optically measures the foam and additionally video records every foam test we perform. We report each video with the lot number of the blended product for future reference. Foaming is the most common compatibility issue when changing oils. Defoamers from manufacturer A can actually conflict with manufacturer B and cause foam. It is not a common thing overall but does occasionally happen. If a foam issue exists it is best to foam test the oil in the lab. By isolating a chemical related foam (if it foams out of the equipment) vs a mechanical induced foam (if in foams in the equipment not the lab) it is very useful to diagnose the ultimate issue. In many cases if you have something that foams the simple solution would be to simply change the oil again. We routinely deal with customers that have reservoirs that are hundreds of gallons and sometimes thousands of gallons. In those cases we design a solution that can be added to their reservoir that will solve the issue.

Next would be an example of what 50 mils of foam looks like during a sequence II foam test. Sequence II is run at 94 degrees C.

Lastly an image of what a trace looks like in a sequence II test. A trace means that there are bubbles that form at the interface with the oil and glass at the perimeter and do not form a layer of foam on top of the oil.

Hopefully this will give some insight into the topic of foam and further what it takes to legitimately understand what you are shipping as a company.

1619723860345.jpeg

Our foam testing stations

IMG_0789.jpeg

50 mils of foam on sequence II

IMG_2394.jpeg

This is a trace, actually a very slight trace of foam in a sequence II test

David
 
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Mola is on the money as usual. There are many types of defoamers with the most common being silicone or methacrylate based. It is probably easier to make some statements that are general with respect to foam. Defoamers have a window of which they work in. More is not necessarily better. In fact if you treat a product with too much defoamer it will actually cause foam that would be much worse than you were originally dealing with. High treat rates of defoamers while reducing foam can actually have a negative effect on air release. Defoamers are very surface active and will cling to surfaces that will deplete their concentration in the oil. Defoamers will be depleted by things like changing filters but not the oil, or transferring from drums to other containers for example. As mentioned above the API allows 50 mils of foam and additionally allows 10 minutes for the foam to break. This is a very loose specification. Our oils will go from a trace of foam to zero in seconds.

We do not treat products any differently based on intended use. We simply ship products that don't foam. Below are some pictures. First of the equipment we use to test for foam. We have 4 testing stations and one dedicated to measuring the cracking pressure and flow rate of the stones used to distribute air into the oil during the foam test. The test is open loop feeding a given amount of air to the stones so the stones must function within a window to be valid. When the stones function outside of this window we will spend $300 on a new one that does. We have invested nearly $100,000 in foam testing equipment. Each foam station has a camera which optically measures the foam and additionally video records every foam test we perform. Foaming is the most common compatibility issue when changing oils. Defoamers from manufacturer A can actually conflict with manufacturer B and cause foam. It is not a common thing overall but does occasionally happen.

Next would be an example of what 50 mils of foam looks like during a sequence II foam test. Sequence II is run at 94 degrees C.

Lastly an image of what a trace looks like in a sequence II test. A trace means that there are bubbles that form at the interface with the oil and glass at the perimeter and do not form a layer of foam on top of the oil.

Hopefully this will give some insight into the topic of foam and further what it takes to legitimately understand what you are shipping as a company.

View attachment 55690
Our foam testing stations

View attachment 55691
50 mils of foam on sequence II

View attachment 55692
This is a trace, actually a very slight trace of foam in a sequence II test

David

I'm impressed 👍
 
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Jul 30, 2003
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When I first bought my little mower with a 2.5hp B&S motor on it, I got very, very irritated with the automatic throttle control thingy that would give it more gas as it bogged down then back off once rpm's climbed. I ripped the device off and wrapped the throttle spring around and cinched it as tight as it would go (holding the throttle wide open). I was very irritated and basically said, 'I can't stand this anymore so I'm gonna blow your little @ss up".

15 years later on Mobil 1 it's STILL running at wide open throttle with absolutely no sign of quitting. It may quit tomorrow but WOW. To me this is incredible. This little mower is used to cut through thick ivy, pine cones, gets choked completely down, crunk back up, etc and just keeps going on PCMO. I'll never be convinced it would have lasted any longer, if this long, on "small engine oil".
 

bchannell

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Jan 9, 2008
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647
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WV
So, bottom line on small engines in OPE is, that foaming is more than likely not an issue to select oil over. Hence, the hyperbole of the small engine manufacturers about using a small engine specific oil for it's anti foaming characteristics.
 
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Jan 22, 2011
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6,024
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Ohio
The question comes up pretty regularly (duh!) about using regular auto oil in small engines. The only real question I've ever had about it is the manufacturers all make a big point of saying small engine oils, (that they sell) have anti foaming additives that keep the oil from aerating. I don't know the chemistry of anti foam agents for oil, but was wondering if anyone had any knowledge on this.
Do all oils have anti foam adds? Are HDEO's better in this respect? Most of my OPE engines are water cooled, with oil pumps, full pressure lubrication and filters, so they can use car oil just fine, but what about an air cooled, oil slinger, that would froth up the oil pretty well?
Never had oil in a small engine foam up with any oil I used. I can see that happening if one overfills their crankcase.
 
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