oil, synth or dino? (nklr)
Posted: Sat Apr 07, 2001 11:55 am
3 emails from the GL1800 list, thought it a pretty good analysis for
a nontechnical person like myself.
I am a NASA Engineer atMarshal Space Flight Center in Huntsville,
Alabama. My field of work is Tribology which is the study of
friction, wear, and lubrication. In our spare time, our group
collects and tests different motor oils using the Shell Four Ball
tester. This tester tests the extreme pressure properties of oils.
These areas in a motor are cam to lifter contacts, valve stem to
guild, and piston skirts. Over the years we have found synthetic
bases oils to out perform mineral based oils by a large margin. We
test the oils new, after 1000 miles, 2000 miles, and up to 10,000
miles. In a nut shell, we found that synthetic oils have better wear
properties after being run 10,000 miles then mineral grade oils new.
Which synthetic do we use? First any you will benefit from any
synthetic, but we use Mobil 1. Mobil by far puts more research
dollars in motor oils then any other company. They are also
aggressive in racing.
Other notes on motor oils.
Do not run a multi grade oil (10w-30) more then 1000 to 2000 miles -
depending on your driving habits.
This is because a 10w30 oil starts its life as a 10 weight oil and
large polymer chains are added to get the 30 rating. These chains
break down very quickly which produces small chains with an open
electron charge at the ends. These ends attract grim and form sludge.
Do not run synthetics in a new rebuild. A new engine needs the added
friction allowed by mineral oils to set the rings properly. Chevy
found this out on the corvette. These cars came from the factory
with
Mobil 1 and owners brought them back because of smoking and oil
consumption (rings did not seat). Run a good single weight oil for
the first 2000 miles. We found Havaline 30 to be a good mineral oil
-
in fact we use it for our standard.
The reason Mobil 1 can safely be run for 10,000 miles is because the
additive package is well engineered to isolate grim and hold it in
suspension. This also is why Mobil 1 is expensive. You know - you
get what you pay for.
I know there are a lot of questions on motor oils. You can e-mail me
for more information or search the web for more details on
synthetics.
Your Roadster deserves the best - run synthetic oils.
_______________________________________________________
I have received a lot of comments on oils, so I will try and cover
some of the concerns/comments.
I listed multi grade oil break down at 1000 to 2000 miles. This is
for the junk oils found at circle K for a dollar. A good name brand
oil will last 3000 miles without too much break down. This is for
mineral grade oils - synthetic oils meet government viscosity tests
for ratings without adding thickeners like polymer chains.
Guys here at work run synthetics in motors that have 140,000 to
170,000 miles on them without any more oil consumption them normal.
I believe that you will get a slight increase in consumption in older
motors because the synthetic are very slippery and can get by old
rings easier. In these cases going to a 15w-50 may help, but this is
not a reason not to use synthetics.
Older motors need the extra protection. At running temperature a
synthetic will maintain its viscosity, where a mineral oil viscosity
is DRASTICALLY REDUCED.
A test on how well synthetics work at different temperature can be
done in your home. Get a quart of your favorite mineral oil and a
quart of a synthetic. Put a cup a each oil in a glass or paper cup
and stick in the freezer over night. In the morning try and pour the
oils out. Next test: DO THIS OUTSIDE. On an old camp stove put a ?
of the synthetic oil in an old frying pan and put it on the stove on
the highest heat setting. Cook for 30 minutes. Now cook your oil
for 30 minutes. At this point you will see why you cooked the
synthetic first. As the oil cooks pour some out to see the changes in
viscosity between the oils.
Part 3 on oil additive coming soon. I need to back to NASA work.
_______________________________________________________
Date: Thu, 15 Feb 2001 07:01:29
Hey all -
The question of change intervals and synthetic oil has come up. As a
side at work we run oil tests using the Shell Four Ball test rig.
This tester was developed by Shell oil to test the extreme wear
properties of motor oils - cams, piston skirts etc. It consists of
three, = inch balls held in a triangular pattern in a cup with oil
heated to 165 degrees. A forth ball is lowered to the center of the
three balls and loaded to 40 KG. The ball is then rotated 600 RPM
for one hour. After the test the wear scar is measured on the three
stationary balls. The bigger the scar the lower the extreme wear
property of the oil is. We use Havoline 30 wt for a base line. We
use this oil because engineers from the past liked this oil, so we
have a large data base.
Looking at data shows new Havoline 30 wt has a wear scar of .0165
inches. New Mobil 1 has a .0145 inch scar. May not seem like a lot
of difference, but it is. Havoline 30 at 3000 miles has a wear scar
of .020 inches and Mobil 1 at 4000 miles has a .0164 scar. Remember -
the bigger the badder. 3000 miles is as long as anyone was willing
to run Havoline 30 wt, so its data stops here. Mobil 1 at 6000 miles
is .0167, at 8000 miles is .0188, and at 10,000 miles is .0194. So,
at 10,000 miles Mobil 1 has better lubrication properties in the
critical areas in your motor then a good 30 wt. All mineral oils
follow Havoline pretty close - major brands. Some off brands have a
.020 wear scar new. Multi-grades generally have a larger wear scar
as well. This data was from a 5.0 Ford Mustang. Every motor will be
slightly different, but not much.
So, synthetic can handle long run intervals. But, that is part of the
story. You have contaminates to deal with. This is where the additive
package comes in play. This is the expensive part of oils and the
reason synthetics are high priced. Because of the long run intervals
of synthetic, they must have a vastly superior additive package - and
they do. Proof of this is to take 3000 mile dino oil and look at it
in a glass jar - then do the same for Mobil 1. The Mobil 1 will look
new compared to the dino oil. I run Mobil 1 in my new cars to the
longest manufactures oil change interval - usually 7000 miles. This
will keep the warranty happy. In my Roadster I change it once a year
regardless of mileage. It run my Roadster about 5000 miles a year.
Most people at work run synthetics and do the same. We have a bunch
of cars in the lot that have over 200,000 miles on them and going
strong. I (my wife) never keeps one that long.
I run 10w-30 Mobil 1 in my new Roadster motors (after break-in).
Older motors get 15w-50 because the tolerances are larger. Because
synthetics don't thin down like mineral oils do at temperature, I
would be careful running 15w-50 in a motor with a high volume oil
pump. By doing so you may run into cavitation problems - oil gage
jumping wildly. Drag racers experience this often at high RPM. Drop
a wt and it will clear up.
I checked the auto parts stores last night and could not find a zero
wt Mobil 1. It was about 2 years ago they were talking introducing
this oil, so apparently they have in some markets. I stand
corrected.
Testing another "magic" oil additive today. It looks and smells like
linseed oil! This should be fun. Additives are another subject all
together. Another day, but never tested a good one - none- zip -
zero
don't waste your money.
Sorry for being soo long. I like synthetics (obviously). If you
have
been to the conferences, seen all the tests and data, and read the
lubrication journals you would run nothing other then synthetics.