Topic: 7 Oil Myths from GM Techlink

[TomatoSoup]

Apropos absolutely nothing, here's an interesting article I found while browsing - especially the bits about zinc additive.  Apologies for the formatting, I cut & paste from the PDF and did a quick manual reformat...

(From: http://www.nonlintec.com/sprite/oil_myths.pdf)

7 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 re
fining conditions, Pennsylvania crude oil made better engine oil than
Texas crude or California crude. Today, with modern re fining methods,
almost any crude can be made into good engine oi l. 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 ring s 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 th e 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 us age. For
over 60 years, ZDP has been used as an add itive in engine oils to provi
de wear protect ion 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 te st 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 increase d 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 pl ace the phosphorus level in the 0.10%
range. However, phosphorus is a poison fo r 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 ashl ess 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 wh ile these oils
work perfectly well in mode rn, gasoline engines equipped with roller
camshafts, they will ca use 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 o il 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
sing le 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 fa ct that the ZDP level of these
new oils is comp arable to the level found 9 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.

[Critterman]

great info thanks.

[JoshMcMadMac]

Where are the other three?