GL-4 vs GL-5

[BOBISTHEOILGUY]

quote:

---

Originally posted by tom slick:
if gl-5 basically exceeds gl-4 as you claim then why do some oems specify gl-4 for certain applications? the 3 different manufactures of worm drive gear reduction units i have (all the same basic design) they all specify mobil SHC 460 which i was told by the local oil guy specs to a gl-4. the previous facility guy filled them with mobil1 (gl-5). one of them failed, the bronze gear completely wore out, and while repairing it is when i found the spec for mobil sch 460.
i am not doubting you that they are interchangeable i just find it interesting that gl-5 has not replaced gl-4 or that any lubes claim to be gl-4/gl-5.

---

As John above posted, there appears that some gear manufactures are posting GL-4 and GL-5 on the same product.

The reason why your bronze gear wore out wasn't because of corrosion but the wrong viscosity oil most likely shearing out the base oil and with not having the proper barrier additives.

After looking up the spec for Mobilgear SHC Series 460 , I see that this oil isn't classified as either, but given the specs, I'd say it falls into a GL-5 with the higher level of Barrier regime protection it offers.

Looking at the cross ref info, the proper cross ref for that lubricant is a gl-5, in our case the
#268 SUPREME GEAR LUBE #460 is the proper replacement for that application.

So back to our point, it's not the Bronze Corrosion issue of a gl4 vers gl5 but actual additive levels of ep for shock and load that is the issue here in your case.

 

[BOBISTHEOILGUY]

quote:

---

Originally posted by moribundman:
I've been warned by other Audi drivers not to put any GL5 tranny fluid in my Quattro. They say it WILL ruin the synchros. Audi demands GL4 for the tranny and the torsen, and GL5 for the rear differential. I guess, I'll just go with the overpriced OEM Audi fluids, because I'm not going to find a concrete answer.

---

I'd never want to go against manufactures recommendations, and that is exactly how it should be.

Myself, I'd investigate their reasons as to how it will ruin synchros, and knowing what I do about synchros and lubricants, I think their full of it and would love to know, how does a gl5 oil cause problems with synchros.

This is just personal opinion in this case and not to be taken as anything more.

[ July 05, 2003, 08:47 AM: Message edited by: BOBISTHEOILGUY ]

 

[BOBISTHEOILGUY]

Yes Al, GeorgeCLS is still a part of our site supporter program. Here's his info...
Exxon/Mobil

 

[moribundman]

Originally posted by BOBISTHEOILGUY:


I'd never want to go against manufactures recommendations, and that is exactly how it should be.

Myself, I'd investigate their reasons as to how it will ruin synchros, and knowing what I do about synchros and lubricants, I think their full of it and would love to know, how does a gl5 oil cause problems with synchros.

This is just personal opinion in this case and not to be taken as anything more.


Bob,

I know nothing but what people have told me about using GL5 in Audi trannies. I guess there is something to the claims, because the Redline site states this:


GEAR AND SYNCHRONIZER WEAR PROTECTION
... Typically, the use of a GL-5 lubricant in a synchromesh transmission will shorten the synchronizer life by one half. The extreme pressure requirements of spur gears and helical gears found in transmissions are not nearly as great as found in rear-wheel drive differentials. A GL-4 lubricant provides adequate protection for most manual transmissions, unless a unique design consideration requires the extra protection of a GL-5.

At this point I'm really confounded by all the differing claims. If I follow Audi's suggestion, then

A - I never need to change either tranny or rear differential oil

B - I have to buy Audi OEM fluids

I don't like suggestion A, and I sure don't like suggestion B. Unfortunately, the manual states only to use fullsynthetic SAE 75W-90 in the tranny and fullsynthetic GL5 SAE 90 in the rear differential. All the warnings about GL5 in the tranny come from fellow Audi owners (A few of whom blamed failed brass/bronze synchros on the high sufur content in GL5), and from statements like Redline's.

 

[widman]

The current sulfur/phos additives aren't what I would call corrosive, but chemically adhere to the bronze, creating a sacrificial layer on the surface. This is a black color. (I have some pics on my site).
Whether this is damaging to the synchronizer depends on the aggesiviness of the surface of the synchronizers. If they can cut through this protective coating and grab, ok. Some are very smooth and spin, heating up and turning a bluish black, destroying the oil faster as well.

 

[Ken2]

quote:

---

Originally posted by tom slick:
if gl-5 basically exceeds gl-4 as you claim then why do some oems specify gl-4 for certain applications? the 3 different manufactures of worm drive gear reduction units i have (all the same basic design) they all specify mobil SHC 460 which i was told by the local oil guy specs to a gl-4. the previous facility guy filled them with mobil1 (gl-5). one of them failed, the bronze gear completely wore out, and while repairing it is when i found the spec for mobil SHC 460.
i am not doubting you that they are interchangeable i just find it interesting that gl-5 has not replaced gl-4 or that any lubes claim to be gl-4/gl-5.

---

The "GL" specs are API Gear Lube specs for cars and trucks. They are not industrial gear lube classifications. Mobil SHC460 is a synthetic gear oil with an ISO viscosity grade of 460. This is roughly equal to an SAE 140 gear oil, but as you saw, you cannot always substitute an oil that meets an auto spec for an oil that needs the industrial spec.

Ethyl Corp. is a major supplier of additive packages to oil blenders and has some excellent reference material on line. Here's what they say about GL-4 and GL-5:
GL-4:
"This classification is still used commercially to describe lubricants, but the equipment required for the anti-scoring test procedures to verify lubricant performance is no longer available. Designates the type of service characteristic of gears, particularly hypoid(2)
in passenger cars and other automotive type of equipment operated under high-speed, low-torque, and low-speed, high-torque conditions. Lubricants suitable for this service are those which provide anti-score protection equal to or better than that defined by CRC Reference Gear Oil RGO-105 and have been subjected to the test procedures and provide the performance levels
described in ASTM STP-512A, dated March 1987(3).

GL-5:
Designates the type of service characteristic of gears, particularly hypoid in passenger cars and other automotive equipment operated under high-speed, shock-load; high-speed, low-torque; and low-speed, high-torque conditions. Lubricants suitable for this service are those which provide anti-score protection equal to or better than that defined by CRC Reference Gear Oil RGO-110 and
have been subjected to the test procedures and provide the performance levels described in ASTM STP-512A dated March 1987(2).
--end quote--

By the way, Schaeffer's GL-5 #267 gear oil does not have the typical sulfur gear oil smell.


Ken

 

[Al]

quote:

---

Originally posted by BOBISTHEOILGUY:

quote:

---

Originally posted by moribundman:
I've been warned by other Audi drivers not to put any GL5 tranny fluid in my Quattro. They say it WILL ruin the synchros. Audi demands GL4 for the tranny and the torsen, and GL5 for the rear differential. I guess, I'll just go with the overpriced OEM Audi fluids, because I'm not going to find a concrete answer.

---

I'd never want to go against manufactures recommendations, and that is exactly how it should be.

Myself, I'd investigate their reasons as to how it will ruin synchros, and knowing what I do about synchros and lubricants, I think their full of it and would love to know, how does a gl5 oil cause problems with synchros.

This is just personal opinion in this case and not to be taken as anything more.

---

My level of knowledge is not up to yours-but I agree with you 100% And you have to agree that this whole subject is not consistant no matter what. No wonder I was so confused

BTW didn't we have an ex Mobil rep on this board a long time ago?? I remember him saying there was no valid current way to test for GL-4 as the testing apparatus is no longer valid. Anyone remember??

 

[JohnBrowning]

Well I never gave this much thought before now. All the Toyotas I have owned have said on of two things (use gl5 XX W XX) or (use gl4 XX W XX or GL5 XX w XX). Well if they are going to give you a choice does it really matter? I do not think that Toyota would allow you to use anything that would shorten the life of their product.

The next thing I was hinking was if I use Redline MTL/MT90 50/50 will I still have thermal stability of a GL5. I know that gl4 is not tested for thermal stability but with it being redline I just expect it. P.S. I have seen Toyota synchros and I am preety sure that they could cut through steak!! They are agressive!

 

[tom slick]

after re-reading my post i was thinking one thing and wrote something else. i didn't mean to imply that the gl-5 gear oil killed the gear unit, mearly that it had the wrong oil in it and i found that out while reading the instructions to repair it. the gear didn't look corroded or discolored at all, just the teeth were worn out, actually gone.

what i was trying to say was why do they still make and sell gl-4 if gl-5 superceeds it? they seem to describe the same application type. why is it not like motor oil and atf's standards where the new rating makes the old rating obsolete? is there still an application that you should only use gl-4? why don't lubes say they are both gl-4 and gl-5?

[ July 09, 2003, 10:05 PM: Message edited by: tom slick ]

 

[Bror Jace]

I know Motul made a manual tranny fluid which claimed to be both a GL4 as well as GL5. And last time I looked, Synergen’s Syngear II gear oil claimed to be GL6.

moribund, don’t give up and just let the stealership have their sordid way with you. There are excellent aftermarket fluids available and they will cost less than the fluids at your dealership … which may only be of mediocre quality anyway.

For the GL4 75W90 tranny fluid, it sounds like Red Line MT-90 is the way to go. It meets the specs exactly. However, for the GL5 differential fluids the number of possibilities are greater. Find out if it is limited slip or not, that’s the biggest consideration to worry about. My guess is that it is but there are plenty of GL5 limited slip fluids available … even pure synthetic ones.

--- Bror Jace

 

[moribundman]

Hmm, not sure about the MT-90 versus the MTL. My fellows Audi enthusiasts seem to favor the 75W-80 instead of the required 75W-90. I've heard of people using either MT-90 or MTL, and some had problems with either. I'm not sure if a Quattro has a limited slip differential in the rear differential. The manual calls for a GL5 SAE 90 gear oil.

Maybe I should try Lubro Moly GL4 75W-90 in the tranny/torsen and GL5 75W-90 in the rear differential. The Liqui Moly site lists those two products for my application.

 

[Bror Jace]

Go with the GL4 Lubromoly if you want, it doesn't have near the reputation and track record of Red Line's synchromesh fluids. In fact, I never knew they made a GL4 for trannies. I thought you were trying to go with "safer" fluids?

Red Line MTL is a 70W80 now (they changed the formula or re-rated it) and not a 75W80. I can't imagine using this stuff in an application calling for 75W90.

As for the GL5, is there's no concern about limited slip, that just deepens the pool of potential brands.

--- Bror Jace

 

[moribundman]

Yeah, once again, everybody says something else about the issue. This is not meant to be criticism, by the way - it's just an observation. That really doesn't make it any easier for me. However, I have one other option. I know Liqui Moly makes engine oil, which has a very good reputation with Audi drivers, but I know little about Liqui Moly gear lube. However, I can use Pentosin gear lube, because Pentosin is an OEM fluid supplier for VW/Audi/Porsche, and I'm sure they can tell me what to use for my Audi. However, it might be problematic to get the Pentosin gear lube in the US.

 

[sciroccoGTX16V]

LiquiMoly only offers 75W-90 GL-5 in USA. But in their German site they list GL-4 and GL-5 too.
Don't worry too much about the additives if you change the gear oil every 40K miles. don't buy into the VW/Audi "lifetime fluid " story. I would use Pennzoils Synthetic lube, i think it sulfate free GL-5 or Redline MTL/MT-90 depending on the climate you are. MTL is a little too thin for my liking, that oil seeps thru everywhere. You can mix them up if you want. Shaeffers gear lube with moly is good but i see their specs list sulfates so i wouldn't keep it in my tranny for long time.

 

[sciroccoGTX16V]

MTL is definitely too thin especially after it gets hot. Lots of people mix MTL and MT-90 as compromise for weather changes. The GL-5 oil should work fine but I wouldn't keep it for too long. If you change gear oil every yr like I do, it's probably safe to use. If you aren't in USA you can probably get some Liquimoly gear oils, i plan on doing so next time I visit Germany.
The sciroccos are the fun cars like the early VWs nowdays new VWs are bloated and "practical" ( two cup holders, arm rest..)

 

[moribundman]

Well, the tranny fluid and rear differential oil have been in that car for 125k miles. I guess a few thousand miles more won't matter anymore.

I'm somehow not fond of mixing those fluids. I've also heard opinions pro MT-90, pro MTL, and opinions against either one. So far I haven't found, lets's say 5 people? who say the same thing.

As for where I am, it says right under my post.

I don't think I have to go for a thin sauce tranny fluid, because it's never cold here. And I sure don't plan on changing the tranny fluid every year. It's a bit late for starting that now with that car.

For now I'll keep looking for more information.

 

[moribundman]

Hey sciroccoGTX16V,
So you also think sulfates may harm the synchros? Good point with the 70W-80 being thin - it's not like Audis don't leak enough already.

PS: I've owned two Sciroccos. An '80 Mars Red GT and an '89 Tornado Red GT (Not available in US at that time).

 

[A4NCAR]

I'm currently using Motul Gear 300 75W-90 in my '03 Audi A4 1.8t 5 spd manual transmission. I recently switched from Red Line's MT-90 (was an avid Red Line user for 7 years). I was warned by some that a GL-5 rated transmission fluid was not compatible (due to brass syncros). But there was some confusion as to whether or not this Gear 300 was imcompatible, or not, because it was rated GL-4/GL-5. I brought this to MotulUSA's attention, since Motul is like OEM for VW/Adui, but I'm still waiting for confirmation from Motul. Both of their 75W-90 manual transmission fluids are GL-4/GL-5, so that seems strange that they would have fluids that were not applicable to VW/Audi trannies. I'm pretty confident that it is perfectly fine. But I'd still like an answer nonetheless from Motul themselves.

I also plan on using it in the center and rear differentials.

[ June 04, 2004, 01:14 AM: Message edited by: A4NCAR ]

 

[TooSlick]

Can't vouch for all the chemistries out there, but I've been using the Amsoil GL-4/GL-5 synthetic gear oils in Vw/Audi transaxles since 1980, with no problems at all. When the time comes to change fluids in my 2002 Audi TT roadster, I'll be installing the Series 2000, 75w-90 in the transaxle and rear differential. I used this same fluid in my '95 Tacoma for eight years and it worked just fine. The additive chemistry they are using is non-corrosive at sustained lube temps < 250F, and most transaxles run at 150F to 180F - even under very heavy loads.

Redline claims you'll cut syncro life by 50% by using a GL-5 lube in a GL-4 application - lets see some actual data on this for any modern GL-4/GL-5, MT-1 formulation? IMHO it is a purposely misleading statement and is one of the main sources of confusion on this subject....

Tooslick
www.lubedealer.com/Dixie_Synthetics

 

[biodiesel]

quote:

---

Originally posted by Bror Jace:
I know Motul made a manual tranny fluid which claimed to be both a GL4 as well as GL5. And last time I looked, Synergen’s Syngear II gear oil claimed to be GL6.

---

Last time I checked there was no such thing as GL6.

Does that exsist now?