<VV> Motor oil shear strenght comparisons - a good article

[Mark Durham]

Joel, and yet Quaker State says they test their oils after the oil has
run a normal oil change interval and the oils still meet fresh oil
standards. I guess you can believe what you want to believe. I'm not
saying the article is God's gift to mankind on oil, but these and
industry tests do give a person a good place to start. What is missing
is how much pressure is really there in the bearing journals and on the
faces of the lifters, cam lobe, and valve stem to rocker areas. Then we
could compare real world pressures to real world shear data.
We already know that Mobil 1 and Amsoil, plus the better synthetics
from other oil suppliers are good oils and will protect our engines
well. What I knew from personal experience was that my corvairs in the
past did very well with the havoline 10w30 and 10w40 Dino oils I fed
it, even some straight weights of 30wt or 40wt, and I put 220k on the
same cylinders and the engine ran fine with little oil useage.
What I learned from this is that it confirmed the synthetics position
in the marketplace, and affirmed there are Dino oils that can do the
same job, but I would never run a Dino oil longer than 3k miles.
One surprise was the relative poor showing of the Mobil 1 15w50 oil,
which has a large following in the Corvair camp, so I presume that even
that oil with its lower numbers still far exceeds the extreme pressure
needs of the Corvair engine as well.
As for me, I will try to use the best oil I can afford, but will
probably stick with one of the higher zddp and higher psi oils for all
my cars. Mark Durham
Sent from my Windows Phone
From: Joel McGregor
Sent: 7/18/2012 11:21
To: Virtual Vairs
Subject: Re: <VV> Motor oil shear strenght comparisons - a good article
There is a huge problem with this test.  It's only on fresh oil which
might make the results useful for break in oil you are only going to
run for an hour or less but they are pretty much meaningless for an
oil you are going to run for 3000 miles.  You might think that if the
protection starts out high then it will stay higher than another oil
but that isn't always or even often true.
The only test I've read where someone tested oil, ran it and tested it
again failed 3 of the 4 oils tested.  The only one that tested good
enough to keep running after 750 miles was Mobil1 and it was down 23%
in viscosity from where it started.  I think Castrol GTX was 2nd ahead
of Honda fully  synthetic oil if I remember correctly.
Joel McGregor
________________________________________
From: virtualvairs-bounces at corvair.org
[virtualvairs-bounces at corvair.org] On Behalf Of Mark Durham
[62vair at gmail.com]
Sent: Monday, July 16, 2012 4:48 PM
To: Virtual Vairs
Subject: <VV> Motor oil shear strenght comparisons - a good article

Gents, I searched to see what reactions other flat tappet forums are
having about the Defy oil. The Corvette Forum has a article by a classic
car guy who did shear testing on 48 oils, including the Defy 10w30.

540 RAT's results, as you will see, may change the way you look at oils,
but keep in mind his focus is on shear strenght, or the ability to prevent
contact. It really is a good supplement to Richard Widman's article on
oil.

The article has changed my belief that synthetic oil is actually better at
protecting your engine. The Industry standard Amsoils and Mobil 1's did not
come out on top in these independent tests, either, and they are good
oils. Many of todays later generation Dino oils for modern engines did very
well in the shear tests, too. Nor was it consistent that a higher weight
oil did better over a lighter weight oil.

While the author says there are "no bad oils in the group", the oils at the
top outperform those at the bottom in shear strenght by a staggering almost
100% margin. That is significant. I think that from now on I will be making
selections at least in the top 10% of the list for all my cars, and add the
ZDDP to that oil as necessary for the Corvair.  By the way, the Defy 10w30
is in the top 10%, and at 15.64 for 5 quarts, is a great buy.

Enjoy the article.

http://forums.corvetteforum.com/c3-tech-performance/3078239-quaker-state-s-new-defy-motor-oil-lab-test-and-wear-test-data.html

Mark Durham
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