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Transfer case oil, GL-4 only!

Posted By: marksroberts61

Transfer case oil, GL-4 only! - 08/27/16 03:45 AM

I got curious about GL-4 and GL-5 since O'Reilly didn't carry GL-4 except for 140 weight, and I ran across this paper. It tells exactly why we don't want GL-5 in our xfer boxes. We might want this on the FAQ page.


The difference between gl4 and gl5 gear oils
Posted By: Kevin C

Re: Transfer case oil, GL-4 only! - 08/28/16 03:34 PM

"Does that make them satisfactory for synchromesh or synchronized transmissions?"

The article addresses the issue with using GL5 in a synchronized gear box.

FYI On a GEN1 and GEN2 there are no synchronizers in the transfer case to have a wear problem with. There are bronze thrust washers. However, the loading and heat level are not sufficient to cause any problems. I have never had the transfer cases apart on the later models.

The transmission is a different story and GL5 can reduce synchro life.
Posted By: marksroberts61

Re: Transfer case oil, GL-4 only! - 08/28/16 07:57 PM

Better safe than sorry. The fluid specifications list GL-4 for the xfer box and GL-5 for the diffs, no 'or' notes that I've seen. Since the 4wd is shift on the fly, up to 65 mph, there must be some sort of synchronization going on. It's true that GL-5 is a better extreme pressure gear lube, as long as you have only steel components.

My main thrust was dissemination of information, and to warn people about the lubes that say they meet both specs, they do as far as extreme pressure goes, but are not safe for yellow metal.
Posted By: Kevin C

Re: Transfer case oil, GL-4 only! - 08/28/16 09:07 PM

The original manual lists GL-4 or higher for both the transfer case and the transmission. There was a TSB in 1993 that corrects that callout for the transmission to Gl-4 only.

Again, for the transfer case its a non issue. I have been running Gl-5 in my transfer case since 1994 without any problem. That includes inspecting parts when I installed lower ratio low range transfer case gears about 12 years ago.

I'm going to go out on a limb here and say that If I haven't had a problem in 22 years, its probably safe. cool

You do bring up a good point that GL-5 is a problem in some applications.

"Modern EP gear oils contain thermally stable additives that promote system cleanliness and do not corrode yellow metals under moderate operating conditions. The goal in formulating top-tier EP gear oils is to develop additive chemistries that will carry high loads under boundary conditions and protect mating surfaces from wear while minimizing corrosiveness to yellow metals and keeping steel gear components clean."

Gear Oil EP additives

I have been running Redline 75-90 Gear GL-5 lube as well as Mobil 1. Same Redline in the front LSD and the rear Torsen. That simplifies what I need to keep on the shelf in the shop.


GL-4 GL-5 TSB reference


Posted By: ES_97Sport

Re: Transfer case oil, GL-4 only! - 08/29/16 07:51 PM

I accidentally put GL-5 into a '97 Montero Sport transfer case several years ago. When I drained the gear oil it looked like liquid gold. Needless to say that was the end of that transfer case. frown

Edward
Posted By: TOASTY

Re: Transfer case oil, GL-4 only! - 08/30/16 01:36 AM

We should have a fluid specification sticky
Posted By: Kevin C

Re: Transfer case oil, GL-4 only! - 08/30/16 06:10 AM

Originally Posted by Kevin C
"Does that make them satisfactory for synchromesh or synchronized transmissions?"

The article addresses the issue with using GL5 in a synchronized gear box.

FYI On a GEN1 and GEN2 there are no synchronizers in the transfer case to have a wear problem with. There are bronze thrust washers. However, the loading and heat level are not sufficient to cause any problems. I have never had the transfer cases apart on the later models.

The transmission is a different story and GL5 can reduce synchro life.


Update... Until I can confirm I should have said no synchros in a GEN 1.
Posted By: ES_97Sport

Re: Transfer case oil, GL-4 only! - 08/31/16 11:11 PM

If I'm not mistaken, the Montero Sport 4WD '97-04 and the AWD '00-04 use the same transfer cases as the Montero Gen 2 and forward? I do know that all the Sport t-cases have syncros so I presume everything post-97 (at least) in the Montero has syncros.

I apologize for asking a stupid question, but what is the generational year boundary for the Montero?

Edward
Posted By: marksroberts61

Re: Transfer case oil, GL-4 only! - 09/02/16 08:15 PM

I understand that people are thinking that it's a corrosion problem, which it's not. The sulphur is buffered so as not to be corrosive. The issue is that the sacrificial boundary layer that forms with GL-5 (GL-4 forms one too, just not as strong) has a surface bond strength that is stronger than the brass itself, thus it is a physical erosion problem. The difference is irrelevant except if you have someone telling you its OK because they have had a synchro sitting in a glass jar of GL-5 for years and it's still ok, so the stuff is good to use. I wasn't aware of the TSB, makes you think about all of the comments here to the effect of "I'm not going to try to outguess the Mitsubishi engineers."
Posted By: ES_97Sport

Re: Transfer case oil, GL-4 only! - 09/05/16 10:34 PM

Originally Posted by marksroberts61
... The issue is that the sacrificial boundary layer that forms with GL-5 (GL-4 forms one too, just not as strong) has a surface bond strength that is stronger than the brass itself, thus it is a physical erosion problem. ....


Which is why driving mine for two months left me with a catch pan full of brass particles and tiny flakes.

Edward
Posted By: marksroberts61

Re: Transfer case oil, GL-4 only! - 09/06/16 05:51 AM

Exactly! I am sorry for your troubles, Edward, we all are working together to keep these babies running!
Posted By: ES_97Sport

Re: Transfer case oil, GL-4 only! - 09/06/16 06:04 PM

Originally Posted by marksroberts61
Exactly! I am sorry for your troubles, Edward, we all are working together to keep these babies running!


No worries! Just me being incredibly stupid. laugh I think I deserved it as I do actually know better. laugh laugh

Edward
Posted By: plh

Re: Transfer case oil, GL-4 only! - 09/07/16 12:19 AM

Owners manual for the '05 says GL4 for the T-Case. GL5 or higher for the differentials
Posted By: Kevin C

Re: Transfer case oil, GL-4 only! - 09/12/16 02:15 PM

A few things on this.

1: The mechanism of why a synchro loses brass due to EP additives is well understood. Under temperature and pressure of a shift the oil film is sheared when the narrow surfaces of the synchros clutch face press against the cone on the gear. Under pressure the oil film sheers, localized temperature increase and the EP additives are activated. The activation of the EP additive corrodes the copper from the brass.

2: The claim author of the article makes that the mechanism for metal loss is based on film strength causing the metal to peal does not appear to be based on any technical article I could find on the SAE web site or searching Google scholarly docs. I found nothing to back his claim. I also checked several tribology publications, same thing the standard explanation is corrosion when the EP additive is activated from temperature and pressure.

3: The author of the article is a retired McDonalds manager. His main professional experience with oil appears to be whatís used in the fryolator. You would typically expect an expert opinion with what appears to be a new explanation of a wear mechanism to come from a white paper or article of an industry insider or someone doing basic research. I reviewed quite a few SAE articles.

4: When making a novel claim, some research or article should be reference. The same author has published hundreds of similar "expert" opinions on Quora. MAny are questions with regards to McDonalds food. Expert on lots of stuff He does give good general advice, but by no means is the end all authority on wear mechanisms ( not compared to the research articles I typically read).


5: The basic claim that Gl-5 is bad for brass synchronizers is true.

6: GL-5 does not harm brass parts that are not subject to film breakage and the resulting increase in temperature. This means that for any GEN1 we can continue to follow the factory recommendation of GL4 or higher in the transfer case.

7: I have run GL-5 in the 4cyl Gen 1 manual transmission. No kittens died, it shifted fine. At the same time, I know that the synchro rings would not last as long.

8: If you have a later model transfer case that has synchros donít use GL-5. The manual and TSB's are a good guide.

Example of a real paper, fun read

Another fun read
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