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GL-5 in Transfer Case and Diffs?

Discussion in '2nd Gen. Tacomas (2005-2015)' started by jmettx, Sep 24, 2016.

  1. Sep 24, 2016 at 5:42 PM
    #1
    jmettx

    jmettx [OP] Active Member

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    Anybody know of any bad issues with using a GL-5 oil in the transfer case or front/rear diffs?
    I put that stuff in my 6speed standard trans and it screwed up my syncros (made of brass, I guess). I don't want to repeat that mistake. I plan to use Red Line 75w-90 on front and rear diffs, as well as transfer case, but Red Line website is saying I should use their GL-5 instead of MT90 product.

    I'm aware of all of the posts out there on this, but wanted to hear if anybody had a bad experience using GL-5 in these applications. Thanks.

    2005 Tacoma, V6, TRD Off Road, 6-speed, NO LSD
     
    Last edited: Sep 24, 2016
  2. Sep 24, 2016 at 10:57 PM
    #2
    landphil

    landphil Wishin' I was Fishin'

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    I used MT-90 in my 6 spd transmission and ran Chevron Delo synthetic GL5 75w90 in the t-case and diffs for a few years with a terrible end result. Thankfully it wasn't a lubricant failure, GL5 is recommended for the diffs and t-case after all. I was concerned of how the tcase would shift on the fly, and it was perfect with the GL5. Oh, and so there is no confusion, this is what I mean by a terrible end result:

    https://www.tacomaworld.com/threads/bad-day-for-my-tacoma-video-added.449839/
     
  3. Sep 25, 2016 at 12:02 AM
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    Norton

    Norton Senior Member

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    Recommend checking your Owner's Manual. Page 458 recommends "GL-5 or equivalent" for use in my (2013) Differentials, while page 460 recommends "Gear oil API GL-4 or GL-5" in the Transfer Case.

    FWIW, page 460 also recommends "Gear oil API GL-4 or GL-5" in the 6MT.
     
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  4. Sep 25, 2016 at 12:08 AM
    #4
    PintSize

    PintSize Crossthreaded & torqued down

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    Agreed. My 2011 manual says GL-4 or GL-5. I ran Mobil1 synthetic 75w90. Yes it performs better, but next gear oil change I plan on using Redline as I've seen some fairly positive suggestions on TW.
     
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  5. Sep 25, 2016 at 5:13 AM
    #5
    jmettx

    jmettx [OP] Active Member

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    @landphil @Norton @PintSize : Thanks guys. As you say, it's always good to look at the manual first, which I did. What I was trying to communicated in my first message is that the Toyota manual is incorrect with regard to this issue with the transmission....it says you can use GL4 or GL5, which is wrong and I learned it the hard way since GL5 messed my syncros. After researching the trans issue, all other reliable sources including TW and Red Line say to never use GL5 in the 05 Taco trans. So, if they made an error in the manual on that point, I thought they could be wrong about the oil specs for the diffs and transfer, too.
     
  6. Sep 25, 2016 at 5:30 AM
    #6
    DaveInDenver

    DaveInDenver Not Actually in Denver

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    It's page 407 in my 2008 owner's manual, but it definitely says GL-4 or GL-5, viscosity 75W-90. I drained whatever was in there when I bought it and filled with Redline MT-90, which is GL-4 exactly for the reason @jmettx mentions, that GL-5 is supposed to be bad for yellow metals and I didn't want to risk it. I used Redline in the other places, which is GL-5 and I think fine for the use.
     
  7. Sep 25, 2016 at 9:31 AM
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    landphil

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    Yes, as a rule, GL5 and synchronized transmissions are a bad combination. Damaging at worst, or reduced shifting performance at best.
     
  8. Sep 25, 2016 at 1:48 PM
    #8
    Norton

    Norton Senior Member

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    With all due respect, I'm not convinced the manual is incorrect. I should have been more explicit in my previous response by stating I used GL-5 rated Amsoil Severe Gear 75W-90 in my '04's 5MT and I currently use it in my '13's 6MT, both with NO problems.

    On what do you base your assessment that GL-5 "screwed up [your] syncros"?
     
  9. Sep 25, 2016 at 5:38 PM
    #9
    jmettx

    jmettx [OP] Active Member

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    @Norton : I know, it sounds crazy and I was surprised myself. But after my experience I researched it and found out the hard way. My personal experience was that on my 05 6-speed, I had a normally functioning trans, and then replaced fluid with GL5 and the trans started to have a slight grind going from second to third when the outside temperature dropped below 60 degrees. The problem would go away after driving for a few miles. Turns out that GL5 is damaging or hindering to so-called yellow metals like brass, especially on syncros, which are found in the 6 speed trans on the 2005s and beyond. It is now a known problem and I've heard that Toyota has changed that spec in later manuals, but I have not investigated to see if that is true. See comments above, but also do a quick search of tacomaworld and you will find other references in this regard. Here is a thorough write up: http://www.widman.biz/uploads/Transaxle_oil.pdf Also, even Red Line says that GL5 should not be used in manual trans due to this problem...here is a reference from them: https://www.redlineoil.com/product.aspx?pid=133. If this problem isn't the case in your 2013 6MT, the only thing I can think of is that they stopped using brass in the trans in the later year second gen models. Hope this helps. Thanks.
     
  10. Sep 25, 2016 at 6:11 PM
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    DaveInDenver

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    I think what Norton is asking is for evidence that GL-5 was actually damaging something, specs of brass coming out with the drained fluid or an oil analysis that shows high levels of copper or bronze in the used lube for example. Without tearing a transmission apart and inspecting the synchros it's hard to really say one way or the other. My $0.02 is that as long as Toyota recommends GL-4 or GL-5 I will use GL-4 in the transmission.

    This question is not recent, it's been a problem for decades. Since the 1980s that I remember and probably before that. The problem is oil companies claim GL-5 is safe for brass (which it is in theory, at least they contain buffered sulfur) and the manufacturers don't really disagree with them.

    They are primarily concerned with the pressure on the faces of their gears and since it's really only Toyota and Nissan still selling stick shifts it's a pretty small number of trucks that it's even a question. It would be interesting to know what Toyota or Aisin fill the transmissions with from the factory, but I'm betting the same GL-5 goes in every hole from the same bulk tank. You really want GL-5 in the diffs and transfer case. Actually you want GL-5 on the steel gears in the transmission, too. It's just the yellow metals that suffer over time.
     
    Last edited: Sep 25, 2016
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  11. Sep 25, 2016 at 6:35 PM
    #11
    Norton

    Norton Senior Member

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    It sounds less crazy than, perhaps, dated. I'm familiar with the problem, but believed it to be a thing of the past. That said, you seem to have answered your own question - If your experience tells you to stick with GL-4 in your MT, why not just do so, regardless of others' experience and what the manual says?

    +1.
     
  12. Sep 25, 2016 at 6:45 PM
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    TRD Larry

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    I have 8 qts. of Mobil1 GL5 75w90 sitting in my garage that I plan to use tomorrow when I change my diffs, transfer case and 6sp manual transmission. I checked the manual and it said GL4 or 5 was good for the transmission. I would hope if that was not correct Toyota would have notified anyone with a 6 sp. That would be the right thing to do.
     
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  13. Sep 25, 2016 at 7:00 PM
    #13
    Norton

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    FWIW and as stated above, I used GL-5 rated Amsoil Severe Gear 75W-90 in my '04's 5MT and I currently use it in my '13's 6MT, both with NO problems. In fact, shifting my MTs IMPROVED when I swapped-out whatever Toyota uses for Amsoil Severe Gear 75W-90.
     
  14. Sep 25, 2016 at 7:28 PM
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    DaveInDenver

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    There seems to be a belief that the Toyota factory service manual has a typo in the torque spec for the leaf spring u-bolts. It says 37 ft-lb and that is much too low and is probably supposed to be 73. I don't know for sure this is true but the u-bolt spec from 1979 to 2004 was 90 ft-lb and 37 just on the face seems awfully low. So it would seem even Momma Toyoda isn't perfect. If GL-5 is what they wanted you to use then why even list GL-4 at all?
     
  15. Sep 25, 2016 at 8:28 PM
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    Norton

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    While I'm not naive enough to believe Toyota publications are without error, I doubt they repeat them year-after-year. With that in mind, I'm forced to wonder why my '04 Owner's Manual ALSO recommended "Gear Oil API GL-4 or GL-5" for the 5MT.

    Why not list them if they're BOTH suitable to the application?
     
    Last edited: Sep 25, 2016
  16. Sep 25, 2016 at 9:07 PM
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    DaveInDenver

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    The U-bolt typo (if that is what it is) exists in all the printed FSM from 2005 to 2011 and AFAIK still exists in the electronic versions. I never got an addendum to my set of books. It's also been repeated in TSBs (such as the leaf spring recall). So it may be intentional but in that case the specification is wrong.
    My experience (which is limited, I'll admit) is that GL-5 is generally a long term wear question on the synchros. It's just an unknown I think. I'm only drawing on my previous experience with a 1991 W56 that went almost 300K with only a couple sets of shifter seats (I just ran factory plastic) and new input and output seals once. I ran plain old dino GL-4 it's whole life. I was the second owner from 100K to 280K and it's still going with the 3rd owner, a friend of mine from the Rising Sun. So unless I see some data that indicates the synchros Aisin puts in the RA60 are some other alloy than what the R-series, W-series and G-series sticks used before I'm more comfortable trusting the accumulated wisdom on this. I have every intention of driving this truck to 250K+ as well and don't want to tempt fate.

    My thinking here is that sometimes we have to trust generally mechanical understanding over what is written in the book. Take what the FSM or owner's manual says, interpret it against common knowledge or even common sense. Maybe what Toyota thinks is an important criteria, perhaps GL-5 runs quieter as the expense of higher wear, isn't what I expect from my truck. A lot of people complain about gear whine, you know. But back 20 years ago trucks were expected to be kind of noisy and clunky so expectations are different. It's the same with motor oil, people are trying to eek out mileage with thinner and thinner oils that might at some point be shown to hit the limit of being able to really protect the crankshaft bearings under heavy loads.

    I don't think there is a wrong answer here. I think if you use GL-4 or GL-5 Toyota will honor their 60K warranty commitment. After that you're on your own and that's what I'm trying to set my truck up for, not needing a transmission at 100K and hopefully it also goes the distance like Toyotas should.
     
    Last edited: Sep 25, 2016
  17. Sep 25, 2016 at 9:40 PM
    #17
    randomguy

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    I run MT90 in the 6mt. Swapped it out at 18k and it made a huge difference in the noise. As long as I own the truck I'll keep filling the transmission with MT90.

    As far as the axles and t-case goes I just use whatever. First service I used Valvoline 75w90(GL-5) dino oil. The oil in the axles was a little gross but not too bad at 30k. The oil in the transfer case could've passed for new.
     
  18. Sep 26, 2016 at 8:58 PM
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    Taco'09

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    FWIW, Toyota dropped the dual use recommendation of either a GL-4 or GL-5 in the transmissions on the later models. Only GL-4 is permitted in the transmission. For the transfer case the dual use is still permitted. For the differentials you only want to use GL-5 because the GL-4 does not have adequate amounts of AW additives, most GL-4s have roughly half that amount of GL-5.
     
  19. Sep 27, 2016 at 5:27 PM
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    jmettx

    jmettx [OP] Active Member

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    Thanks to everybody who replied. I always appreciate the good advice on TW. Since I started this thread, I'll go ahead and finish it.
    There's a lot of mixed opinions out there on this topic, but after doing a lot of research, talking to a lot of guys and trying out a few things, here's what I recommend to anybody who finds this thread later. When it comes to 2nd gen Tacoma with a manual trans, your best bet is:

    Use a GL-4 75W90 oil if you have a manual transmission. While the manual may say you can use GL4 or GL5, there is enough evidence out there that makes the GL4 product (like Red Line MT90) a safer bet. Apparently the chemistry of the GL5 harms so-called yellow metals like brass in your trans, but also the extra slippery properties of GL5 can cause meshing problems with syncros.

    For your diffs and transfer case, use a GL-5 75W90 gear oil. I use Red Line, but there are lots of other choices out there. Note that if you don't have the LSD, Red Line still recommends that you use their standard 75W90 GL5 gear oil which has friction modifiers. They make a version of this oil without the friction modifier additive, but I spoke to the factory and they still recommend the standard product for diffs w/o LSD. Also, I read that while GL5 is absolutely the right product for the diffs, some guys say that since the transfer case has one or more syncronisers, they prefer to use a GL4 product just because of the known issue with using GL5 in the MT (I haven't been able to confirm this last statement about the transfer case, but seems legit).

    I recognize that not everybody will agree with what I wrote here and I don't want to start the whole debate over again. What I listed above is the conclusion I came to after a lot of research and experiencing the problems noted with GL5. See info and links listed earlier in this thread for more info. Thanks, guys.
     
    landphil likes this.

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