Just what is the GL-4 spec

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All I can find is generic explanations and that it is an obsolete spec. Seems the original testing equipment has been disappeared.

So just what is the spec?
 
My explanation won't be any better, probably worse.

I'm guessing from what I read eons ago, but I think it has less sulfur than GL-5 gear oil.
Sulfur is bad for "yellow metals" often used in manual transmissions along with it making the gear oil too slippery for fast shifting.
GL-4 gear oils are less slippery and provide better and faster shift quality when used in manual transmissions.
 
Originally Posted By: SHOZ
All I can find is generic explanations and that it is an obsolete spec. Seems the original testing equipment has been disappeared.

So just what is the spec?


No,whomever published that GL-4 is an OBSOLETE specification is WRONG!

GL-5 does NOT supersede GL-4 specifications, instead it is meant for a
totally different application.


GL-4 has different and lesser amounts of friction modifiers
which is designed for manual transmissions with synchronizers
which contain softer yellow metals like brass. Usually there is very little or no sulfur based modifiers in this specification.

Using GL-5 with high levels of sulfur based friction modifiers
can eat away and seriously damage soft yellow metals like brass in those synchronized manual transmissions.
 
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Originally Posted By: GiveMeAVowel
Originally Posted By: SHOZ
All I can find is generic explanations and that it is an obsolete spec. Seems the original testing equipment has been disappeared.

So just what is the spec?


No,whomever published that GL-4 is an OBSOLETE specification is WRONG!

GL-5 does NOT supersede GL-4 specifications, instead it is meant for a
totally different application.


GL-4 has different and lesser amounts of friction modifiers
which is designed for manual transmissions with synchronizers
which contain softer yellow metals like brass. Usually there is very little or no sulfur based modifiers in this specification.

Using GL-5 with high levels of sulfur based friction modifiers
can eat away and seriously damage soft yellow metals like brass in those synchronized manual transmissions.



Here's the usual info found when looking for the spec, pretty vague.

Quote:
GL-4 Active The designation API GL-4 denotes lubricants intended for axles with spiral bevel gears operating under moderate to severe conditions of speed and load or axles with hypoid (see note)gears operating under moderate speeds and loads. These oils may be used in selected manual transmission and transaxle applications where MT-1 lubricants are unsuitable. The manufacturer's specific lubricant quality recommendations should be followed.


Quote:
API to Retire GL-4 Spec
By Stephen Swedberg

On July 1 the American Petroleum Institute polled its Lubricants Group on declaring the GL-4 gear oil category a “service designation not in current use.”

If approved, API GL-4 will become obsolete on July 31.

API GL-4 has been a part of the gear oil family for many years, denoting lubricants intended for axles with spiral bevel gears operating under moderate to severe conditions of speed and load or axles with hypoid gears operating under moderate speeds and loads.

Although this service designation is still used commercially, some test equipment used for performance verification is no longer available.

At the May 5 meeting of the API Lubricants Group, Kevin Buzdygon from ExxonMobil Research and Engineering recommended that GL-4 be made obsolete because it is impossible to run most of the required tests.

Currently, according to the latest (1995) edition of API publication 1560, “Lubricant Service Designation for Automotive Manual Transmissions, Manual Transaxles, and Axles,” said Buzdygon, the following are active industry specifications for automotive gear oils:

– API GL-1 : mildly loaded gearing, products are just base oil (no test requirements).
– API GL-4 : moderately loaded gearing (original tests listed in ASTM STP 512A-1986).
– API GL-5 : highly loaded and/or high speed gearing (now ASTM D7450).
– API MT-1 : heavy duty non-synchronized manual transmissions (now ASTM D5760).

GL-4 is most often used in older gear sets. Some of them are truck applications where the loads are not very heavy as well as older automobiles. GL-4 gear oils also found some applications in industrial gear sets that were very heavily loaded but were not offset.

As car designs went to lower profiles and before front wheel drive became common, rear axles had to go to very high offset hypoid gears. That results in some terrific loads on the gear teeth as the power is transmitted to the rear wheels from the engine. GL-5 became the oil of choice with those designs. GL-5 was always the choice for heavy duty trucks and off-road vehicles since the shock loads and wear are so great in those applications.

MT-1 is a relatively recent addition and is specifically designed for manual transmissions. It has load carrying capabilities similar to GL-4 but has extra wear, corrosion and antifoam capabilities to deal with the transmission.

Buzdygon noted that most API GL-4 tests listed in ASTM STP 512A have been unavailable for over 14 years. With the exception of some older additive technologies, API GL-4 quality claims cannot be supported as originally intended by ASTM STP 512A. This means that an alternate means of supporting API GL-4 quality claims would be necessary.

As far back as 1987, at least one test was known to be unavailable and the category was considered obsolete, Buzdygon continued. Since that time, a new specification has remained unsettled within ASTM.

Without access to the required tests, additive suppliers and lubricant marketers tend to use one or both of the following methods to support API GL-4 claims, said Buzdygon.

Under the “50 percent treat rate” approach, if API GL-5 quality can be documented for a given treat rate of an additive package, then half the treat rate of that additive package is deemed to provide API GL-4 quality. This approach is not documented in any API, SAE, or ASTM publication, but it is used frequently in the industry, Buzdygon said, and although this approach may have been valid in the past, being based on actual test data, this approach would not necessarily apply to untested additive chemistry.

A second method is to document performance by running selected tests that are similar to the original API GL-4 tests listed in ASTM STP 512A. However, technical judgment is required to make a proper choice of test method and test results, and varies greatly within the industry, said Buzdygon.

API’s Kevin Ferrick recommended to the Lubricants Group that since it is not possible to run most of the tests required for API GL-4 the specification should be made obsolete. The consequences of making API GL-4 obsolete are minimal and public recognition of API GL-4 claims is not expected to change very much, he noted. Lube marketers may need to adjust the language used to make API GL-4 claims and the “50 percent treat rate” approach should not be used without a reasonable level of additional supporting documentation.


In 2006, the latest year for which reliable data are available, U.S. gear oil sales totaled 33 million gallons, according to the National Petrochemical and Refiners Association.
 
Just to note you will still find MANY brand new vehicles that
specifically call for GL-4 only.

While API might want to retire that spec it is still widely used around the world and especially in Europe on light duty
manual transmissions with synchronizers to this day.

Also it wasn't noted as a follow up whether or not API actually retired the GL-4 specification it only spoke of IF they would retire it.
 
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Originally Posted By: MolaKule
Any GL-X spec is primarily a gear protection spec.

GL-4 is commonly specified for manual transmission and transaxle gear and bearing protection.

http://www.bobistheoilguy.com/forums/ubb...tion#Post729255


Hey Molakule, could you please comment on these AFTON ways of achieving GL4 ?

Here's a "premium" add pack for transmissions, specifically for GL-4, ZDDP based etc.
http://www.aftonchemical.com/ProductDataSheets/Driveline/HiTEC-353_PDS.pdf

Here are a couple of other products, that are GL5/GL4...
http://www.aftonchemical.com/ProductDataSheets/Driveline/Axcel-S_PDS.pdf
https://www.aftonchemical.com/ProductDataSheets/Driveline/HiTEC-343_PDS.pdf

The GL4 is achieved with the same additive in both cases at half treat rate (which supports an internet myth, but the dedicated GL4 dispells that myth).

I take it if I could choose an oil formulated with the first of the additives, genuine GL4 target, I would have a better manual trans solution than the multipurpose half treat rate examples.

And there's no way of knowing without VOA which direction a bottle on the shelf is made from.
 
Originally Posted By: Shannow
Originally Posted By: MolaKule
Any GL-X spec is primarily a gear protection spec.

GL-4 is commonly specified for manual transmission and transaxle gear and bearing protection.

http://www.bobistheoilguy.com/forums/ubb...tion#Post729255


Hey Molakule, could you please comment on these AFTON ways of achieving GL4 ?

Here's a "premium" add pack for transmissions, specifically for GL-4, ZDDP based etc.
http://www.aftonchemical.com/ProductDataSheets/Driveline/HiTEC-353_PDS.pdf

Here are a couple of other products, that are GL5/GL4...
http://www.aftonchemical.com/ProductDataSheets/Driveline/Axcel-S_PDS.pdf
https://www.aftonchemical.com/ProductDataSheets/Driveline/HiTEC-343_PDS.pdf

The GL4 is achieved with the same additive in both cases at half treat rate (which supports an internet myth, but the dedicated GL4 dispells that myth).

I take it if I could choose an oil formulated with the first of the additives, genuine GL4 target, I would have a better manual trans solution than the multipurpose half treat rate examples.

And there's no way of knowing without VOA which direction a bottle on the shelf is made from.


Without an expensive lab analysis, there is no way to tell exactly what is in there.

A bit of formulating history may explain things a little.

Many years back, the only way to achieve a GL-4 rating was to use either a commercial additive package or mix your own. When I started out, I mixed my own individual components.

As far as commercial additives, the only way to do it back then was to take a sulfur-phosphorus EP gear oil additive package and use a treat rate of 1/3 to 1/2, and use a low treat rate of ZDDP as the primary anti-oxidant, and add the friction modifier.

Later, a special ZDDP-based package was offered with additional anti-oxidants, metal inhibitors, rust inhibitors, emulsifiers, and synchro friction modifiers. The HiTec 353 and the Lubrizol equivalent uses this combo.

Today, we use a special multi-funtional phosphate ester package that contains a powerful aminic-phenolic antioxidant, with added metal inhibitors, rust inhibitors, emulsifiers, and synchro friction modifiers.
 
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