The Subaru SVX World Network   SVX Network Forums
Live Chat!
SVX or Subaru Links
Old Lockers
Photo Post
How-To Documents
Message Archive
SVX Shop Search
IRC users:

Go Back   The Subaru SVX World Network > SVX Main Forums > Technical Q & A

Reply
 
Thread Tools Display Modes
  #1  
Old 09-17-2002, 08:18 PM
alacrity024
Guest
 
Posts: n/a
There's like 16 different kinds of Mobil 1!!

So I was at the local AutoZone today picking up supplies for an oilchange, and on the shelf where there's usually two different weights of Mobil 1 (I've been buying the 10w-30 with the green cap) there were no less than five different varities.

A couple that I can remember were "european car formula" and "performance driving formula." The latter of which I'm sure is a big seller with the Import Kids who only have to buy 3 quarts of it for their little 1.8-liter four bangers

Anyhow, both the European formula and the Performance formula were 0w-xx Can someone please just give me a brief oil weight explanation and then do their best to elaborate a little on whether or not this "performance driving" Mobil 1 is just a bunch of snake oil BS?

-Adam
Reply With Quote
  #2  
Old 09-19-2002, 09:16 PM
lee lee is offline
Registered User
 
Join Date: Mar 2002
Location: Indialantic, Florida
Posts: 2,940
from Valvoline, then from Mobil

from the Valvoline web site:

by Wayne Scraba

Most people are familiar with oil's Viscosity Rating—SAE 10W-40, for example. However, very few know that the "W" refers to "winter," not "weight." And most of us have no idea what the weight-rating numbers mean other than that the vehicle's manufacturer specifies a particular viscosity. This story deals strictly with viscosity; we're saving the petroleum vs. synthetic debate for later.

Oil Duties

Inside an engine, oil is in a Catch-22 scenario: It has to seal rings and valves, but it also must reduce friction. In simple terms, oil has to accomplish two functions that have directly opposite requirements.

The viscosity of any oil changes with temperature. The higher the temperature, the lower the viscosity—the oil thins out. On the flipside, the lower the temperature the higher the viscosity. Because of this, the Society of Automotive Engineers (SAE) has established a series of classifications that establish oil viscosity at 100 and 0 degrees Celsius (212 and 32 degrees Fahrenheit, respectively).

Highs and Lows

Low-viscosity oils flow better than high-viscosity ones—the lighter-weight fluid is easier to pump and therefore circulates faster through the engine's various galleries. Low-viscosity oils also maintain a lower oil pressure, but the oil pump delivers a greater volume through the galleries than it would with thicker (higher-viscosity) oils. Heavier oils also tend to operate at higher temperatures because the oil pump has to work harder to force the lubricant through the system. Oil does not compress readily, so the added pressure increases the temperature. In the end, high-viscosity oils maintain a higher oil pressure, but the pump delivers a smaller volume of oil.

Multigrades

Multigrade oils typically begin as base oils, such as 10W. Then viscosity-index modifiers (polymers) are added in an effort to stabilize the viscosity. This allows a SAE 10W-40 oil to flow like a 10W at cold temperatures and a 40W at higher temperatures.

The multigrade oils' viscosity modifiers are long-chain molecules that lessen the change of viscosity with temperature variance. In the past, the polymer additives (used to thicken the oil) were sometimes susceptible to viscosity loss. Permanent viscosity loss occurred when high shear forces (such as the relationship between the main bearings and the crankshaft) actually break the polymer molecules into less-effective smaller pieces. On a similar note, temporary viscosity loss also occurred when the polymer molecules aligned themselves in order to create a path of least resistance.

Fortunately, today's additive packages have improved oil's shear-resistance. However, oils with the same rating from different manufacturers can exhibit different viscosity ratings in an operating engine, depending on the shear stability of their viscosity-modifying additives.

For technoids, weights are defined thusly (stokes and centistrokes are measurements of viscosity):

"SAE 30 is SAE 30 no matter what the "W" prefix number is: 0W, 5W or 10W. This viscosity in centistokes (cSt) @ 100 degrees C is with the minimum of 9.3 cSt and a maximum of 12.5 cSt.

"SAE 40 is SAE 40 no matter what the "W" prefix number is: 5W, 10W, 15W or 20W. The viscosity @ 100 degrees C is within the minim of 12.5 cSt and a maximum of 16.3 cSt.

"SAE 50 is SAE 50 no matter what the "W" prefix number is: 5W, 10W, 15W or 25W. The viscosity @ 100 degrees C is within the minimum of 16.3 cSt and a maximum of 21.9 cSt.

"SAE 60 is SAE 60 no matter what the "W" prefix number is: 10W, 15W or 25W. The viscosity @ 100 degrees C is within the minimum of 21.9 cSt and a maximum of 26.1 cSt.

"There is no SAE 70 and no one is likely to make one with a "W" prefix number although it is possible using a synthetic base oil. This viscosity is identified as Grade 70. The viscosity @ 100 degrees C has a minimum of 26.1 cSt and no maximum."

The difference between a multigrade and a singlegrade oil: The singlegrade can't pass the low temperature viscosity test. If it did meet one of the following "W" viscosities, it would be a multigrade.

Singlegrade oils will become obsolete for performance engines in the future. We dropped SAE 30 and SAE 40 because SAE 10W-40 does everything 30 or 40 can do—and some things the straight grades can't do—like increasing horsepower. If an off-roader doesn't like SAE 10W-40, then use 20W50. It can do everything a SAE 10W-40 can do except pass the sub-zero viscosity test at -20 degrees C.

Multigrade viscosities are run at six different sub-zero temperatures. When a racing-oil designer puts a formula together, he has to know the viscosity at 100 degrees C of every component in the additive composition. He has to have a target viscosity objective for the finished oil in each SAE grade. Once a formula is established, the technician who supervises the blending has to duplicate this formula in the correct proportions every time the product is blended. The viscosity at 100 degrees C has a plus or minus written into the oil's quality-control specification.

Multigrade or Multi-Vis?

One oil manufacturer claims that "some people in the industry use multi-viscosity as if it means the same thing as multigrade. An oil cannot be multi-viscosity, but it can be multigrade by meeting the viscosity requirements for SAE 30, 40, 50 or 60 and one of the sub-zero "W" viscosity requirements. At one time, some oil companies labeled oils SAE 10W, 20W30—as if the oil could be 10W and 20W at the same time. This is impossible because 10W is measured at -25 degrees C and 20W is measured at -15 degrees C, which eliminates the multi-viscosity theory."

API Numbers

Shortly after WWII, the American Petroleum Institute (API) developed a system that established three basic types of engine oils: regular, premium and heavy-duty. Naturally, three oil classifications could never hope to cover all of the different applications ranging from conventional passenger cars to heavy-duty trucks. The API eventually realized that other variables had to be considered, such as the type of engine and its usage. In 1952, the API launched the service classifications system.

The API system revolves around two general classification: S for Service (typical passenger cars and light trucks) and C for commercial applications (typical diesel equipment). The breakdown of "S" varieties is as follows:

SA: This is a plain mineral oil that doesn't contain additives common in today's high-tech lubricants. This oil was primarily used in the 1920s and is obsolete today.

SB: Lubes that contain anti-wear and oxidation inhibitors as well as corrosion inhibitors. This oil was primarily in use prior to 1964 and was created for vehicles that saw moderate conditions. API SB oils are still recommended today by some compressor manufacturers, but should never be used in modern gasoline engines.

SC: This classification was originally recommended for use in 1964-67 vehicles. It contains additives that control rust, wear, corrosion and engine deposits. It too is now obsolete.

SD: SD lubes were recommended for use in 1968-70 vehicles as well as certain post-1970 passenger cars. This oil contains the same additive packages as the SC class and can be used in place of it. It too is now obsolete.

SE: This category was recommended for certain 1971 vehicles as well as most 1972 - 1979 vehicles. This classification offers more protection than the SD group of lubricants and is suitable for severe-duty applications. This classification can be used in place of SD oils. It too is now obsolete.

SF: Recommended for 1980 - 1989 passenger vehicles. This oil has superior anti-wear properties and enhanced oxidation stability over SE lubricants. It too is now obsolete.

SG: The SG rating was introduced in 1989 and combined the performance properties of the commercial rating CC (lubricants designed for use in supercharged/turbocharged diesel applications in moderate to severe service). It too is now obsolete.

SH: Now obsolete, SH was designed for 1996 and older engines.

SJ: Introduced in 1996, this rating is for all automotive engines presently in use.

SL: Introduced in 2001, SL provides improved overall performance for 2002 model year vehicles, including oxidation resistance, deposit control, fuel economy, and low temperature properties.

Generally speaking, think of the API system as a blueprint for oil. In order to gain an API classification, oil manufacturers have to follow a set of limitations. This creates a few problems for oil companies, especially those who produce racing oils. Racing oil must conform to viscosity-grade standards but not necessarily to those for chemical-additive composition or base-oil composition. That's why you'll find several brands of racing oil without API classifications.

Mobil

Their various formulations have some differences in the additive package. For example, the difference in motorcycle oil is the amount of moly added (more may make the wet clutches slip - but it does make the oil "slipperier") - like that's a word. Anyway, some formulations are really just weight variations - European is a 0W-40. BTW: Mobil recommends Super Syn 10W-30 for the SVX. For tech details, refer to this page from Mobil's web site.

http://dallnd6.dal.mobil.com/Apps/DS...0?OpenDocument

Sorry this was so long. You didn't ask an easy question.

Last edited by lee; 09-19-2002 at 09:18 PM.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 05:12 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
© 2001-2015 SVX World Network
(208)-906-1122