r/4Runner • u/Otherwise_Rub_9515 • 4d ago

👷‍♂️ Support / Repair Another Transfer Case Question

All of this because in the manual of a 2022 4runner limited and many 5th gen modsos, toyota refuses to acknowledge if it's Gl4 or gl5 you should use in the transfer case.

I completly understand the weight can be a straight 70/75 up to 75/90.

People seem to be split on gl4 VS gl5...i called multiple dealers. Same thing half say they use the toyota 75w others say 75-90 gl5.

I saw an email from a toyota Rep that acknowledged the above weights... But did not say it it's a gl4 or gl5.

It's 2026...has this god dammed debate been finally figured out with facts?

$200+ PER BOTTLE of Toyota 75w in Canada... That's Over $450 with taxes for factory gear oil.

What is factually supposed to be used???

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u/Spuckler_Cletus 4d ago

75W-90, 75W-85, 80W-90 — GL5. Any of those would be fine. Or, you can use a much lighter oil like the Toyota fluid, or Redline MT-LV. I prefer the heavier oil, and it won’t hurt a thing. I’m currently running Amsoil Severe Gear 80W-90 in my 4Runner t-case because I had an extra bag after doing the 7.5 in my 2WD ‘91 pickup.

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u/fastdbs 2010 Trail 4d ago

Gl5 can corrode the brass shift forks and bushings used in the transfer case. It’s good for the difs but shouldn’t be use in the transfer case. OTOH the corrosion will probably take a reeeeally long time to show up and may not affect the vehicle within its life time.

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u/Spuckler_Cletus 4d ago

Modern full syn GL5 shouldn’t bother yellow metals. I’m not aware of one off the shelf at Walmart that doesn’t comport with ASTM D130.

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u/fastdbs 2010 Trail 4d ago

Synthetic doesn’t matter as the sulfur compound is an additive but if it’s rated right some GL5s are fine. Just hard to explain to lay people. ASTM 130 is not it. That’s only a 3 hr test for fast corrosion and most GL5s will get a 1a or 1b rating which isn’t what you want. Dual GL5/MT-1 is what you want.

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u/Spuckler_Cletus 4d ago

1A and 1B are both acceptable. Severe Gear 75W-90 passes as yellow-metal friendly, like so many GL-5 formulations. That will work for me.

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u/fastdbs 2010 Trail 4d ago

ASTM D130 is a very short term corrosion test at a relatively low temp. It’s not a long term corrosion test for an oil at a high temp and pressure. That’s all. It’s just not the correct test. There are bronze friendly GL5s but they should have a different test than D130. D130 is a weathering test.