Bryan;
I think some of these lubricant tests are cases of comparing apples &
oranges. I doubt if the lubrication requirements of a ball or roller
bearing (Timken) have much in common with a hydrodynamic oil- film
bearing like rod or main bearings. Four-ball & Pin/V-Block tests are
basically extreme pressure lubrication tests. Most of the time when an
engine bearing fails it isn't the fault of the oil that was used.
Regards, Neil Tucson, AZ
-----Original Message-----
From: owner-land-speed@autox.team.net
[mailto:owner-land-speed@autox.team.net] On Behalf Of Bryan Savage
Sent: Wednesday, March 23, 2005 12:08 PM
To: List Land Speed
Subject: Oil testing note
From Lube-Tips newsletter published by Noria Corporation
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Q & A: Engine Oil Performance Testing
"I have seen a number of lubricant manufacturers refer to the four-ball
wear scar test as an indicator of how well the oil will protect an
engine.
Other larger companies tend to brush off the results of this test
indicating
that it isn't representative of actual engine conditions adding that
because
it is cheap to run, the results aren't worth much.
What are your thoughts on this?"
The four-ball test (ASTM D4172) is often used as a screening test for
many
different lubricant types that contain antiwear additives or similar
base oil
properties. Other tribo-mechanical bench tests are often used as well,
including the Timken Test (ASTM D2782) and the Pin and V-Block
(ASTM D2670). Because engines have different contact geometry, loads,
metallurgy and speeds, numerous bench tests and test protocols are
needed.
It is not uncommon for several oils to be tested using two such methods
and
to find that the performance rankings between the oils to reverse (no
correlation).
This is why, among other reasons, passenger car motor oils and
heavy-duty oils
(diesel crankcase) are tested in actual engines using controlled methods
such as
ASTM D5533 Sequence IIIF D5302 Sequence VE.
Jim Fitch, Noria Corporation
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