GL-4 vs GL-5 -- and a letter from Mobil

[Bror Jace]

moribunman, I agree with HardBodyLoyalist. I think it’s a combination of CYA and one hand of a massive corporation ignorant of what the others are doing.

I too believe that the most up-to-date GL-5 gear oil formulations with modern additive packages are safe in applications where yellow metal components are present.

I think that some of these CYA recommendations we are seeing is the fear that you might find an old, old container of oil in your basement and use that. Advising against the use of 10W-40 motor oils is another good example of out-of-date precautions.

But with synchromesh oils like 75W-90 MT-90 available for about the same price, why take the chance when the transmission calls for a GL-4?

Interesting theory Fuelrod, but I just don’t that’s the case. I think the danger is in companies using the cheapest anti-wear compounds available ... the kind of stuff you’ll see in the $1-2 per quart lesser brands ... as well as the stuff which has sat around for many years. Companies charging up to $8-10 per quart for their gear oil can often afford to use the better compounds.

Thanks, Spitty, for that pertinent story!

--- Bror Jace

PS - IF ANYONE GETS A THOUGHTFUL, COMPETENT AND USEFUL RESPONSE FROM THE CUSTOMER SERVICE DEPARTMENT OF A MAJOR PETROCHEMICAL COMPANY, PLEASE FRAME IT, TAKE A PICTURE OF IT AND POST THE PIC HERE ON BITOG!!

 

[heyjay]

GL-4 gear oils are still quite common in the HD trucking industry. For the most part, HD transmission OEM's like Eaton/RoadRanger prefer the GL-4 lubes for increased resistance to heat and better seal protection.

Although synchronized HD transmissions are very rare (MAN in Europe??) the GL-4 vendors claim better compatibility with synchronizers.

I used to have pails of Mobil MobilTrans SHC 50 GL-4 for my fleet. I needed the SHC 50 to keep my extended warranties:

http://www.mobil.com/USA-English/Lubes/PDS/NAUSE2CVLMOMobiltrans_SHC_50.asp

http://www.roadranger.com/NASApp/cs...&blobtable=MungoBlobs&blobwhere=1082221064736

I purchased new a 1990 Toyota 4Runner with 5spd that speced GL-4. Second gear went shortly after I took delivery, and it was in the Toyota shop off and on for transmission problems until they put in a new transmission.

I drained and refilled with SHC 50 and it worked flawlessly. I still did yearly drains and refills, and over 200,000km it shifted perfectly.

I would guess the vast majority of LD transmissions would work well running a GL-5. If the vendor demands a GL-4, there has to be a very good reason.

The only problem with SHC 50, as far as I can tell, is it's only available in 5g pails. I suppose that would last you the rest of the vehicle life?

 

[Fumes]

Is not Amsoil GL4/GL5 compatible? I have a GearVendors OD and it requires GL4 (because the OD section is made in Eur) and have been using Amsoil.

 

[srivett]

It would be nice if I could find some synthetic GL-4 in Sudbury. This is a city of 100,000 and I can not find any! I hear the synthetic Redline is excellent in cold weather but it isn't marketed properly...that's probably why people are desperate to put GL5 in their GL4 transmissions. When I start out in the morning with -40C temperatures and non-synthetic GL4 the shifter feels like I'm paddling a boat through a lake of molases.

Steve

 

[Spitty]

They don't sell Penzoil in Sudbury?

 

[MolaKule]

I keep seeing this GL4/GL5 topic pop up all the time and there is one point I think people miss and that is the following (IMHO):

A GL can have a dual rating to indicate compatibility with copper alloys such as bronzes and brasses. However, a GL manual transmission lube SPECIFICALLY designed to GL4 characteristics has a targeted viscosity and the Proper Friction Modifiers to effect wear reduction and to improve shift quality, respectively.

Bottom line is, most of the GL4/5 dual rated lubes are designed for hypoid differentials and for heavy-duty manual (truck) transmissions, but are NOT designed to match Friction characteristics for sychronizers in daily drivers, NOR are they designed to have the correct viscosity for cold weather shifting.

 

[heyjay]

quote:

---

Originally posted by srivett:
It would be nice if I could find some synthetic GL-4 in Sudbury. This is a city of 100,000 and I can not find any! I hear the synthetic Redline is excellent in cold weather but it isn't marketed properly...that's probably why people are desperate to put GL5 in their GL4 transmissions. When I start out in the morning with -40C temperatures and non-synthetic GL4 the shifter feels like I'm paddling a boat through a lake of molases.

Steve

---

Steve:

Talk to your local Esso Bulk Lube dealer. Good news: I'm sure he'll have plenty of synthetic GL-4 in stock. Bad news: the smallest container may be a 20 litre pail.

 

[99]

Anyone here that's into Jeeps knows all about the GL5 issue with the brass syncros in the AX transmissions. Most run Redline's GL3/4 lubes after finding out GL5 is a no no.

 

[Tremo]

RP MaxGear is both GL4 and GL5 rated.

 

[1sttruck]

The NV4500 needs a synthetic GL-4; Castrol Syntorque (sometimes Syntorq), 75W-85 or sometimes 75W-90, synthetic lube. They package it for GM (PN 12346191) and Dodge (PN 4637579). I paid about $17 a qt at Dodge, and Standard Transmission has it for less than $60 a gallon.

People using other stuff can report back after about a decade and at least 250k miles, on how the synchros operate and look compared to using Syntorq. In the meantime I'm using Syntorq.

 

[wileyE]

quaker state has a full synthetic GL4, qt. part# 56125 on the bottle I have

They stock and use it at our local Q-state monkey-lube, it was cheaper than the dealer fluid.

 

[widman]

This topic will never go away. There is a lot of confusion out there, partly because a lot of companies like to say there products are for all applications, such as the universal ATF's. It is false to say that GL-4 is obsolete. Many brands say their GL-5 can be used in GL-4. The actual performance will vary due to several factors.
1. Some transmissions recommend GL-4 just because it is the minimum protection needed. GL-5 will work fine.
2. Some transmissions Spec GL-4 because they bave bronze, but the bronze is only the yoke, so in reality there is little actual bronze wear surface.
3. Some transmissions should probably not have GL-5 for the heavy sulfur/phos additive, but the aggressive cuts/canals in the synchronizer can cut throug the surface easily enough to not disturb normal driving.
4. Some GL-5 oils are buffered, offering less copper corrosion than non-buffered types.
5. Some oils, like Delo Gear Lube, do not use Sulfur/Phos additives. They use a Borate package that is totally harmless to yellow metals, so it can be put in anything at all (except LSD applications).
Many people expect that because in the API engine oil categories a higher rating means better protection, the sameis true in gear oils. This is not the case.
The other confusion is in GL-6, which is technically obsolete because they no longer make the test equipment, but is designed and formulated to provide higher wear resistance in high angle gears than a GL-5. Several vehicle makers recommend GL-6, even though the API page lists it as obsolete.