GL-5 in place of GL-4

[MolaKule]

Quote:
If GL-4 is indeed obsolete, some other spec must have take its place. I will ask them about that also.


As stated many times, GL-4 is indeed obsolete, but that doesn't mean that manf. will cease specifying GL-4 lubes.

Quote:
GL-1; Specified for spiral-bevel and worm gear axles and some manual transmissions under very mild service. Usually contains rust and oxidation inhibitors with pour point depressants and anti-foamants. Most R&O oils or AW hydraulic oils will suffice here.

GL-2; Specified for worm gear service more than can be satisfied by GL-1. Most R&O oils or AW hydraulic oils will suffice here.

GL-3; Specified for manual transmissions and spiral-bevel axles under moderately severe service. Most Tractor Hydraulic fluids (THF) or AW hydraulic fluids will suffice here.

GL-4; Specified for hypoid gear service under severe service but without shock loading. This classification is essentially obsolete but is still specified by some manual transmission/transaxle manufacturers. Implies an EP/AW additive package that contains 30% to 50% less S-P additives than the GL-5 service classification. Some Marine Gear Lubes fall into this classification, especially the full Synthetic Marine Gear lubes and specialty blenders MT lubes that use high levels of esters.

 

[MolaKule]

I know some are confused, but what I have explained and described is simply the real world situation.

I suggested to the SAE some time ago that a special MT lubricant classsification system be given to passenger car and Light truck MTL's (since they're are not going away) based on a three-tier viscosity system, one for the 6-7.5 cSt range, one for the 9.5 to 11cSt range, and finally, the 14.5 cSt or the 75W90 MTL.

The classification proposed would be called GL-MX where X would be equal to L, M, H, respectively, covering each of the viscosity ranges above.


The following MINIMAL tests would be required and standards set for each:

Kinematic Viscosity @ 100°C, cSt (ASTM D-445)
Kinematic Viscosity @ 40°C, cSt (ASTM D-445)
Viscosity Index (ASTM D-2270)
Flash Point, °C (°F) (ASTM D-92)
Pour Point, °C (°F) (ASTM D-97)
4-Ball Wear 75°C, 1200 rpm, 40kg, 1 hr.
Brookfield Viscosity @ -40°C
Foam Stability (ASTM D-892)
Copper Corrosion (3 hr, 121°C) (ASTM D-130) 1A
Falex Procedure B (ASTM D-3233) (failure load, lbf.)
Brookfield Viscosity, cP (150,000 Max) @-40°C

 

[MolaKule]

For example, if a manufacturer specified Pennzoil Synchromesh or equivalent, it would have to meet GL-MH.

 

[moribundman]

Originally Posted By: MolaKule

As stated many times, GL-4 is indeed obsolete, but that doesn't mean that manf. will cease specifying GL-4 lubes.


I would like to hear your definition of "obsolete."

 

[MolaKule]

There is technical obsolescence and functional obsolescence.


While the GL-4 has become technically obsolete due to the testing equipment no longer being available, the functional part of the GL-4 spec has not. So for GL-4 MT lubes and GL-3 worm gear lubes, the "functional" part of the spec is NOT obsolete.

 

[Audi Junkie]

What about dual-rated 4&5?

 

[MolaKule]

Quote:
What about dual-rated 4&5?


Which one, differential lubes or manual transmission lubes?

I can only speak to our former manual transmission and differential lubes.

For one of our dual rated manual transmission lubes, this meant that the EP protection rating was that of a GL-5 and was compatible with ALL transmission materials used in functionallly rated GL-4 equipment. This was due to the fact that a few transaxles had some hypoid gearing in them.

For our two non-racing diffy lubes, they had functional ratings from GL-1 to GL-5 due to the EP protection additives and compatiblity with ALL materials used in GL-1 to GL-5 rated gear requirements.

 

[moribundman]

Originally Posted By: MolaKule
There is technical obsolescence and functional obsolescence.


While the GL-4 has become technically obsolete due to the testing equipment no longer being available, the functional part of the GL-4 spec has not. So for GL-4 MT lubes and GL-3 worm gear lubes, the "functional" part of the spec is NOT obsolete.


Then you should have been more precise in using the term. If we "gots" adjectives, we "gots" to use 'em for the sake of clarity.

Audi just got back to me. All current Audi manual transmissons specify still GL-4 lubricant. G052911 A (75W-90 GL-4).

Audi, currently using a "technically obsolete" transmission fluid spec, despite "the testing equipment no longer being available." I'll have to get back to them regarding the latter part.

 

[unDummy]

I would think that many automakers are afraid of 'LSD' additives which are common to GL5 gear oils. So, they simple require the GL4 gear oil to reduce the wimpy wristed shift complainers.

Synlube MT, Motul Gear 300, Torco SGO/RTF, and Redline 'NS' are examples of a GL5 without the LSD additives for those of you that want/need the GL5 in a manual. Ford even stocks a GL5 without LSD additive.

For GL4, Amsoil MTF and Redline MT90 are my recommendations. Again, Ford dealers stock a GL4 90wt. And, if you want something thinner, you can get 75w85 GL4 MTF from most of the automakers. You just have to research automaker fluid PN's.

Royalpurple is one of those dual rated, GL4/GL5 fluid. Its a GL5 gear oil with LSD additive that is friendly to manuals that require a 90wt.

The issue with manuals is usually moisture or excessive heat related. I've used Mobil-1 75w90 GL5 for multiple manual transmissions with no synchro issues. And, shift quality was usually better then factory fill. Never lost a synchro or anything with M1 in it. I also recommend 30k gear oil changes or every 2-3 years whichever comes 1st.

To think, the thread asked about a 'front axle' and had nothing to do with manual transmissions. Probably can get away with ANY gear oil there. I would just fill it with the GL5.

MT-1, I believe, is a spec for non-synchronized transmissions only.

Then you have the SAE50 fluids for OTR use. Some are GL4 rated, tend to be on the thick side, and work well in warmer climates in manuals that require 90wt GL4 fluids.

 

[Audi Junkie]

This thread turned out to be quite thorough.