Engine Oil Myth Busters
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Engine Oil Myth Busters
Engine oil myths:
Oil Myths from GM Techlink
Bob Olree, GM Powertrain Fuels and Lubricants Group
Over the years there has been an overabundance of engine oil myths. Here are some facts you
may want to pass along to customers to help debunk the fiction behind these myths.
The Pennsylvania Crude Myth
This myth is based on a misapplication of truth. In 1859, the first commercially successful oil
well was drilled in Titusville, Pennsylvania.
A myth got started before World War II, claiming that the only good oils were those made from
pure Pennsylvania crude oil. At the time, only minimal refining was used to make engine oil
from crude oil. Under these refining conditions, Pennsylvania crude oil made better engine oil
than Texas crude or California crude. Today, with modern refining methods, almost any crude
can be made into good engine oil. Other engine oil myths are based on the notion that the new
and the unfamiliar are somehow “bad.”
The Detergent Oil Myth
The next myth to appear is that modern detergent engine oils are bad for older engines. This
one got started after World War II, when the government no longer needed all of the available
detergent oil for the war effort, and detergent oil hit the market as “heavy-duty” oil.
Many pre-war cars had been driven way past their normal life, their engines were full of sludge
and deposits, and the piston rings were completely worn out. Massive piston deposits were the
only thing standing between merely high oil consumption and horrendous oil consumption.
After a thorough purge by the new detergent oil, increased oil consumption was a possible
consequence.
If detergent oils had been available to the public during the war, preventing the massive
deposit buildup from occurring in the first place, this myth never would have started.
Amazingly, there are still a few people today, 60 years later, who believe that they need to use
non-detergent oil in their older cars. Apparently, it takes many years for an oil myth to die.
The Synthetic Oil Myth
Then there is the myth that new engine break-in will not occur with synthetic oils. This one
was apparently started by an aircraft engine manufacturer who put out a bulletin that said so.
The fact is that Mobil 1 synthetic oil has been the factory-fill for many thousands of engines.
Clearly, they have broken in quite well, and that should put this one to rest.
The Starburst Oil Myth
The latest myth promoted by the antique and collector car press says that new Starburst/API
SM engine oils (called Starburst for the shape of the symbol on the container) are bad for older
engines because the amount of anti-wear additive in them has been reduced. The anti-wear
additive being discussed is zinc dithiophosphate (ZDP).
8
Before debunking this myth, we need to look at the history of ZDP usage. For over 60 years,
ZDP has been used as an additive in engine oils to provide wear protection and oxidation
stability. ZDP was first added to engine oil to control copper/lead bearing corrosion. Oils with
a phosphorus level in the 0.03% range passed a corrosion test introduced in 1942. In the
mid-1950s, when the use of high-lift camshafts increased the potential for scuffing and wear,
the phosphorus level contributed by ZDP was increased to the 0.08% range.
In addition, the industry developed a battery of oil tests (called sequences), two of which were
valve-train scuffing and wear tests. A higher level of ZDP was good for flat-tappet valve-train
scuffing and wear, but it turned out that more was not better. Although break-in scuffing was
reduced by using more phosphorus, longer-term wear increased when phosphorus rose above
0.14%. And, at about 0.20% phosphorus, the ZDP started attacking the grain boundaries in the
iron, resulting in camshaft spalling.
By the 1970s, increased antioxidancy was needed to protect the oil in high-load engines, which
otherwise could thicken to a point where the engine could no longer pump it. Because ZDP
was an inexpensive and effective antioxidant, it was used to place the phosphorus level in the
0.10% range.
However, phosphorus is a poison for exhaust catalysts. So, ZDP levels have been reduced over
the last 10-15 years. It's now down to a maximum of 0.08% for Starburst oils. This was
supported by the introduction of modern ashless antioxidants that contain no phosphorus.
Enough history. Let's get back to the myth that Starburst oils are no good for older engines.
The argument put forth is that while these oils work perfectly well in modern, gasoline engines
equipped with roller camshafts, they will cause catastrophic wear in older engines equipped
with flat-tappet camshafts.
The facts say otherwise.
Backward compatability was of great importance when the Starburst oil standards were
developed by a group of experts from the OEMs, oil companies, and oil additive companies.
In addition, multiple oil and additive companies ran no-harm tests on older engines with the
new oils; and no problems were uncovered.
The new Starburst specification contains two valve-train wear tests. All Starburst oil
formulations must pass these two tests.
1 Sequence IVA tests for camshaft scuffing and wear using a single overhead camshaft
engine with slider finger (not roller) followers.
2 Sequence IIIG evaluates cam and lifter wear using a V6 engine with a flat-tappet system,
similar to those used in the 1980s.
Those who hold onto the myth are ignoring the fact that the new Starburst oils contain about
the same percentage of ZDP as the oils that solved the camshaft scuffing and wear issues back
in the 1950s. (True, they do contain less ZDP than the oils that solved the oil thickening issues
in the 1960s, but that's because they now contain high levels of ashless antioxidants not
commercially available in the 1960s.)
Despite the pains taken in developing special flat-tappet camshaft wear tests that these new
oils must pass and the fact that the ZDP level of these new oils is comparable to the level found
necessary to protect flat-tappet camshafts in the past, there will still be those who want to
believe the myth that new oils will wear out older engines.
Like other myths before it, history teaches us that it will probably take 60 or 70 years for this
one to die also.
Bob Olree, GM Powertrain Fuels and Lubricants Group
Over the years there has been an overabundance of engine oil myths. Here are some facts you
may want to pass along to customers to help debunk the fiction behind these myths.
The Pennsylvania Crude Myth
This myth is based on a misapplication of truth. In 1859, the first commercially successful oil
well was drilled in Titusville, Pennsylvania.
A myth got started before World War II, claiming that the only good oils were those made from
pure Pennsylvania crude oil. At the time, only minimal refining was used to make engine oil
from crude oil. Under these refining conditions, Pennsylvania crude oil made better engine oil
than Texas crude or California crude. Today, with modern refining methods, almost any crude
can be made into good engine oil. Other engine oil myths are based on the notion that the new
and the unfamiliar are somehow “bad.”
The Detergent Oil Myth
The next myth to appear is that modern detergent engine oils are bad for older engines. This
one got started after World War II, when the government no longer needed all of the available
detergent oil for the war effort, and detergent oil hit the market as “heavy-duty” oil.
Many pre-war cars had been driven way past their normal life, their engines were full of sludge
and deposits, and the piston rings were completely worn out. Massive piston deposits were the
only thing standing between merely high oil consumption and horrendous oil consumption.
After a thorough purge by the new detergent oil, increased oil consumption was a possible
consequence.
If detergent oils had been available to the public during the war, preventing the massive
deposit buildup from occurring in the first place, this myth never would have started.
Amazingly, there are still a few people today, 60 years later, who believe that they need to use
non-detergent oil in their older cars. Apparently, it takes many years for an oil myth to die.
The Synthetic Oil Myth
Then there is the myth that new engine break-in will not occur with synthetic oils. This one
was apparently started by an aircraft engine manufacturer who put out a bulletin that said so.
The fact is that Mobil 1 synthetic oil has been the factory-fill for many thousands of engines.
Clearly, they have broken in quite well, and that should put this one to rest.
The Starburst Oil Myth
The latest myth promoted by the antique and collector car press says that new Starburst/API
SM engine oils (called Starburst for the shape of the symbol on the container) are bad for older
engines because the amount of anti-wear additive in them has been reduced. The anti-wear
additive being discussed is zinc dithiophosphate (ZDP).
8
Before debunking this myth, we need to look at the history of ZDP usage. For over 60 years,
ZDP has been used as an additive in engine oils to provide wear protection and oxidation
stability. ZDP was first added to engine oil to control copper/lead bearing corrosion. Oils with
a phosphorus level in the 0.03% range passed a corrosion test introduced in 1942. In the
mid-1950s, when the use of high-lift camshafts increased the potential for scuffing and wear,
the phosphorus level contributed by ZDP was increased to the 0.08% range.
In addition, the industry developed a battery of oil tests (called sequences), two of which were
valve-train scuffing and wear tests. A higher level of ZDP was good for flat-tappet valve-train
scuffing and wear, but it turned out that more was not better. Although break-in scuffing was
reduced by using more phosphorus, longer-term wear increased when phosphorus rose above
0.14%. And, at about 0.20% phosphorus, the ZDP started attacking the grain boundaries in the
iron, resulting in camshaft spalling.
By the 1970s, increased antioxidancy was needed to protect the oil in high-load engines, which
otherwise could thicken to a point where the engine could no longer pump it. Because ZDP
was an inexpensive and effective antioxidant, it was used to place the phosphorus level in the
0.10% range.
However, phosphorus is a poison for exhaust catalysts. So, ZDP levels have been reduced over
the last 10-15 years. It's now down to a maximum of 0.08% for Starburst oils. This was
supported by the introduction of modern ashless antioxidants that contain no phosphorus.
Enough history. Let's get back to the myth that Starburst oils are no good for older engines.
The argument put forth is that while these oils work perfectly well in modern, gasoline engines
equipped with roller camshafts, they will cause catastrophic wear in older engines equipped
with flat-tappet camshafts.
The facts say otherwise.
Backward compatability was of great importance when the Starburst oil standards were
developed by a group of experts from the OEMs, oil companies, and oil additive companies.
In addition, multiple oil and additive companies ran no-harm tests on older engines with the
new oils; and no problems were uncovered.
The new Starburst specification contains two valve-train wear tests. All Starburst oil
formulations must pass these two tests.
1 Sequence IVA tests for camshaft scuffing and wear using a single overhead camshaft
engine with slider finger (not roller) followers.
2 Sequence IIIG evaluates cam and lifter wear using a V6 engine with a flat-tappet system,
similar to those used in the 1980s.
Those who hold onto the myth are ignoring the fact that the new Starburst oils contain about
the same percentage of ZDP as the oils that solved the camshaft scuffing and wear issues back
in the 1950s. (True, they do contain less ZDP than the oils that solved the oil thickening issues
in the 1960s, but that's because they now contain high levels of ashless antioxidants not
commercially available in the 1960s.)
Despite the pains taken in developing special flat-tappet camshaft wear tests that these new
oils must pass and the fact that the ZDP level of these new oils is comparable to the level found
necessary to protect flat-tappet camshafts in the past, there will still be those who want to
believe the myth that new oils will wear out older engines.
Like other myths before it, history teaches us that it will probably take 60 or 70 years for this
Laughing Gas
Joined: Sep 2012
Posts: 1,100
Likes: 5
From: Georgia
I thought the first one was interesting since my dad refused to use PA oil saying it had higher wax content which caused more sludge.
Here's a thread with some interesting comments about some things that are sort of glossed over or ignored in Olree's piece.
GM debunks ZDDP myths for flat tappet cams | Passenger Car Motor Oil (PCMO) - Gasoline Cars/Pickups/Vans/SUVs | Bob Is The Oil Guy
There are also several links to other commentary.
Here's a thread with some interesting comments about some things that are sort of glossed over or ignored in Olree's piece.
GM debunks ZDDP myths for flat tappet cams | Passenger Car Motor Oil (PCMO) - Gasoline Cars/Pickups/Vans/SUVs | Bob Is The Oil Guy
There are also several links to other commentary.
Elder User
Joined: Nov 2009
Posts: 891
Likes: 0
From: Mayfield, KY
Thanks for the post. Getting ready to fire up my rebuild with a mild performance cam. I did buy zinc additive for the break in oil but will not use after I drain as I read that several oils contain up to 13% . The article mentioned Castrol GTX, Valvoline and Rotella, and these are excellent priced oils available everywhere.
Laughing Gas
Joined: Oct 2007
Posts: 916
Likes: 89
I use Valvoline oil in all of my engines , modular and push rod engines.
I have never had a failure in my flat tappet 347 stroker , pushing 500 hp.
I used Valvoline from day one , over 15 years , and countless bottles of nitrous , and it is a daily driver slash weekend drag car.
I am eased some one has posted a myth buster to this .
I have never had a failure in my flat tappet 347 stroker , pushing 500 hp.
I used Valvoline from day one , over 15 years , and countless bottles of nitrous , and it is a daily driver slash weekend drag car.
I am eased some one has posted a myth buster to this .
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From: SW Va
SN/Gf-5 engine oils don't have anywhere near 14 parts/million (.14) zinc/phos any more, they're running more like 6-8 parts/million (.06-.08). Some dual rated Diesel/Gas engine engine oils have around 11-12 (.11-.12).
As the article noted, too much phosphor (above 14% - .14) is a bad thing for iron parts as in tests increased wear was noted & above .20 it attacked the iron grain boundaries so would cause cam spalling. Those oils also had a higher sulfated ash residue, so contributed to combustion chamber deposit loading & the phos was hard on the cat converter.
The newer oils have lowered the zinc/phos back to levels that solved the old cam spalling problems & have a lower sulphated ash (which will help lower combustion chamber deposit loading), to attempt to lengthen cat converter life & thats ok for most unmodified engines that don't have higher than factory loading on the cam & crank shaft. More expensive multipurpose adds are used in the newer recipe lubes, like moly, boron, titanium, calcium, are used & the newer oils cost more, but last longer.
Lots of oil recipe tinkering going on now, so its an interesting time trying to keep up with it all, to see whos recipe performs best in our individual engines & drive cycles.
Nearly all of the SN/GF-5, 5W-20 & 5W-30 lubes are showing increased NOACK % evaporation, so we need to keep a Closer watch on our crank case oil level during the oil change intervial.
For instance, if the oil we choose has a 15% = .15 NOACK evaporation rate oil & we have a 5qt sump, that means we can loose (5qtsX32oz=160ozX.15=24oz=3/4 of a qt loss during an oil change, due just to evaporation alone, not counting whats leaking out, or being consumed by the engine!!!
BUT, not All SN/GF-5, 5W-20, or 5W-30 oils have suffered increased NOACK % evaporation, some blenders that are using highly refined GTL base oils have Lowered their NOACK % evaporation, so it pays for us to shop around, if we have developed a sudden unexplained oil consumption problem, right after beginning the use of SN/GF-5 lubes a year or so ago!!!!
As the article noted, too much phosphor (above 14% - .14) is a bad thing for iron parts as in tests increased wear was noted & above .20 it attacked the iron grain boundaries so would cause cam spalling. Those oils also had a higher sulfated ash residue, so contributed to combustion chamber deposit loading & the phos was hard on the cat converter.
The newer oils have lowered the zinc/phos back to levels that solved the old cam spalling problems & have a lower sulphated ash (which will help lower combustion chamber deposit loading), to attempt to lengthen cat converter life & thats ok for most unmodified engines that don't have higher than factory loading on the cam & crank shaft. More expensive multipurpose adds are used in the newer recipe lubes, like moly, boron, titanium, calcium, are used & the newer oils cost more, but last longer.
Lots of oil recipe tinkering going on now, so its an interesting time trying to keep up with it all, to see whos recipe performs best in our individual engines & drive cycles.
Nearly all of the SN/GF-5, 5W-20 & 5W-30 lubes are showing increased NOACK % evaporation, so we need to keep a Closer watch on our crank case oil level during the oil change intervial.
For instance, if the oil we choose has a 15% = .15 NOACK evaporation rate oil & we have a 5qt sump, that means we can loose (5qtsX32oz=160ozX.15=24oz=3/4 of a qt loss during an oil change, due just to evaporation alone, not counting whats leaking out, or being consumed by the engine!!!
BUT, not All SN/GF-5, 5W-20, or 5W-30 oils have suffered increased NOACK % evaporation, some blenders that are using highly refined GTL base oils have Lowered their NOACK % evaporation, so it pays for us to shop around, if we have developed a sudden unexplained oil consumption problem, right after beginning the use of SN/GF-5 lubes a year or so ago!!!!
Lead Driver
Joined: Nov 2000
Posts: 6,596
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From: Albuquerque
I'd agree that low zinc insn't neccessarily bad for older engines.,but..........I'f you don't add zinc for breakin of a flat tappet cam you are almost garunteed to ruin the cam. The cam companies are all in agreement on this I believe.
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Posting Guru
Joined: Jan 2003
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From: PA
I know, old thread, but I know a person who did just as you say. An acquaintance put new style oil in his fresh built 426Hemi. Ruined the cam and had to re do the whole engine.
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If a manufacturer recommends a particular recipe lube & proceedure to perform a particular task on something they've made, why not follow their suggestions, as who else knows more about the product & its needs, than the manufacturer!!!!
Hotshot
Joined: Mar 2007
Posts: 10,101
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From: Pa
The manufacturer often uses/recommends less than optimal products because certain requirements have to be met. Not because it is the best for performance, longevity and etc.The OEMs primary concern seem to be the vehicles makes it out of the warrenty period before failure while meeting the BS requirements of .GOV.
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