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Recommended oil weight for rear differential

Discussion in '1st Gen. Tacomas (1995-2004)' started by Backinblack03, Jun 24, 2013.

  1. Jun 25, 2013 at 5:59 AM
    #21
    Petrol

    Petrol Well-Known Member

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    Madjik Man you may be absolutely correct when speaking about synthetics, I can't really comment. For regular oil, GL-5 is not simply an improved version of GL-4, they are totally different ratings. GL-5 oils contain additives (sulfur compounds I believe) that attack yellow metals, such as the brass synchronizers used in some manual transmissions. Those additives are a good thing when all steel components are used but are decidedly bad when there is copper in the mix. GL-4 oils can work with hypoid gears as can GL-5 oils but the GL-5 is Not "backwards compatible" with GL-4 when brass components are involved. It may be a total non-issue with synthetics, I don't know.
     
  2. Jun 25, 2013 at 6:37 AM
    #22
    Madjik_Man

    Madjik_Man The Rembrandt of Rattle Can

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    Yeah, you speak the truth.

    Which is why the thread of mine I linked in here was prefaced with, "my mind is still scrambled"

    I hope the 75w-90 synthetic I'm about to put in my rear diff w/locker will suffice
     
  3. Jun 25, 2013 at 6:47 AM
    #23
    bamadawg2009

    bamadawg2009 Member

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    3" spacer in the front and AAL in rear with 3"body kit. I wish I had just went ahead and done a 5inch full suspension lift with 3in body lift.
     
  4. Jun 25, 2013 at 7:55 AM
    #24
    Buckoma

    Buckoma Well-Known Member

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    I think synthetic oils are safe for copper and brass because the sulfur in them is a special compound additive and not the organic sulfur of dino oil. I remember reading about research tests and the syn oils didn't yellow copper.
     
  5. Jun 25, 2013 at 6:19 PM
    #25
    Petrol

    Petrol Well-Known Member

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    Good point and makes sense. Beyond the GL-4/5 and synthetic discussions we also have the 75W90, 80W90, 85W90 arguments about gear oil that all acts like 90 weight when it's hot! Now that issue will just stir some folks up.

    I think it's far better to worry about clean, uncontaminated gear oil than how thick it is for the first mile in the morning. (of course I don't live in Alaska either)
     
  6. Jun 25, 2013 at 8:50 PM
    #26
    thunderone

    thunderone Somewhat financially stable

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    It is all 90 weight when hot. That's why they all end in "90". The beginning number is the rating when cold. The lower the number, the less viscosity it has. That's why running a lower weight oil (for the beginning number) is better in colder environments.
     
  7. Jun 26, 2013 at 4:32 AM
    #27
    Petrol

    Petrol Well-Known Member

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    Precisely
     
  8. Jul 30, 2013 at 6:48 AM
    #28
    Backinblack03

    Backinblack03 [OP] Well-Known Member

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    ABS? What ABS?
    I haven't looked all that closely yet, but what's the best plan of attack on the front differential? It looks fairly well protected...
     
  9. Jul 30, 2013 at 7:38 AM
    #29
    Buckoma

    Buckoma Well-Known Member

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    Take off the skid and it's right there. Use the same stuff that you used for the rear. Just be careful about not stripping the allen-style bolt.
     
  10. Jul 30, 2013 at 7:40 AM
    #30
    jlove1974

    jlove1974 Active Member

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    Here's how critical it is to me:

    I had filled both the boxes with shifters with Redline shockproof lightweight gear oil. I bought a gallon of it at a local speed shop for $50, which is a lot of dough for gear oil. Especially when I had bought a gallon of Supertech 80W90 for $8 last year. But I used Redline Syn because those boxes have gears smaller than a half-dollar, plus syncros. Shockproof lightweigh is the film strength of 140W oil at the slipperiness of an 80W. It's also slick as owl snot sliding down a tree. They use it in Nascar transmissions and Offroad trucks so it's good enough for my DD.

    However, In the two diffs, with gears larger than a half-dollar.........

    I proceed to take approx. 5/8 of a gallon of Supertech 80W90 I had left, took the leftover pint of Redline Shockproof and dumped it into the ST gallon jug, creating the world's most unique Toyota synthetic blend (not to be sold at dealers). I then bought another quart of ST synthetic 75w90 for $5, dumped it into the gallon jug. I then mixed this precious fluid vigorously for several days by letting it sit in the jug.

    I now plan on adding this supremely prolific lubricant into the well-worn cases of my front and rear diff, which have been running the factory lube for 100K miles.

    That's how critical it is. Oh, and in the end, at operating temp, it's going to be the viscosity of 90W gear oil.
     
    Last edited: Jul 30, 2013
  11. Aug 1, 2013 at 5:53 AM
    #31
    Backinblack03

    Backinblack03 [OP] Well-Known Member

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    ABS? What ABS?
    Well, that sounds like fun... I'd better start spraying all the skid plate bolts now then. I don't think they've been touched since the truck rolled off the assembly line...
     
  12. Aug 2, 2013 at 6:33 AM
    #32
    jlove1974

    jlove1974 Active Member

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    redline racing oils
    I'd suggest using a gallon jug and a pump unless you want to take off the front bash plate, which I did not. The hose can snake around and you can easily pump 1.1qts I think it took 50 pumps on a 'sta-lube' type pump that screws into a jug.

    Also, I took an engine cleaning wand and some purple cleaner and cleaned the fill and drain plugs as they were CAKED with mud. lots of stuff lives behind that skid plate. I just took mine off and plan on pressure washing it at the car wash it was so caked with oil and mud. The oil was from some idiot at an oil change place I'm sure.

    Also, if you do alot of water crossing or mudding and haven't extended the front breather hose, I wouldn't spend big bucks on synthetic for the front axle. It it more important to change it if it's been exposed to water. Water in a diff = BAD.

    And the multi-viscosity thing: the further away in numbers, the less 'stable' the fluid unless it's synthetic. I would never run a 5W40 oil unless it was group III+ synthetic oil.
    Same thing with a 75W140. The factory calls for 90W max, and my frankenblend is more or less a 90W gear oil with perhaps a little more 'lubricity' due to the synthetic blended in.

    If you really want to put a lubrication propeller hat, go over to bitog (bob is the oil guy) and read up on their gear oil forums. Way too much info over there.
     
    Last edited: Aug 2, 2013
  13. Aug 29, 2013 at 1:24 PM
    #33
    Backinblack03

    Backinblack03 [OP] Well-Known Member

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    ABS? What ABS?
    Is the hex drive size 9mm for the front diff? I used my calipers to measure the plugs, but they are rusted all to hell as expected. I should probably replace them anyway. Are they a dealer-only part or can someone share an alternate source?
     
  14. Aug 29, 2013 at 1:31 PM
    #34
    OffroadToy

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    I believe the hex head is 10mm... gets torqued to 29 ft lbs.
     
  15. Aug 29, 2013 at 1:31 PM
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    TheCookieMonster

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  16. Aug 30, 2013 at 5:12 AM
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    Petrol

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    `I used a hex drive but I can't remember the size, it was close to 10mm IIRC, it may have even been close enough to an English size that a 3/8 worked. A 3/8" hex drive is slightly smaller than 10mm and will sometimes work on a 10mm (female) hex. It works out to somewhere between 9mm and 10mm, so that's gives you another option if you can't get a 10mm drive to seat. As for replacing the plugs, if the threads are ok and the hex socket isn't beat up, wire brush them clean, paint the outside if you wish (I wouldn't brother) and put them back in. They are essentially steel pipe threaded plugs and there isn't much that can go wrong with them if the threads are OK.
     
  17. Aug 30, 2013 at 5:29 AM
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    TACO TX

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    For all and FTW! 75-90
     
  18. Sep 15, 2013 at 9:41 PM
    #38
    bama trd

    bama trd Well-Known Member

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    Got a 2003 2.7L 5 speed 4x4 with 102K miles. Just bought it 3 months ago , pretty sure the Differentials and Transfer case hasn't been changed. By reading these threads I need to go with Mobile 1 75-90. Question is...How many Quarts should I buy to drain and refill Front, Rear , and Transfer Case? Thanks in Advance
     
  19. Sep 15, 2013 at 10:41 PM
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    Norton

    Norton Senior TW Member

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    I run Amsoil Severe Gear 75W-90 in mine. According to their data sheet, capacities are as follows:
    - Manual Transmission = 5.3 pts
    - Transfer Case = 2.1 pts
    - Front Differential = 2.3 - 2.5 pts (depending on Auto-Disengaging or not)
    - Rear Differential = 5.3 - 5.7 pts (depending on Limited Slip or not)
     
  20. Sep 15, 2013 at 10:49 PM
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    bama trd

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    Thanks! Mine didn't come with an Owners Manual..
     
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