Diff & Transfer case fluid selection

Valvoline squeeze bag 75w90 synthetic from any store does the trick.

 

If I’m not mistaken, GL4 is recommended for manual transmissions as it has less detergents and cleaners that specifically may damage the manual transmissions synchros.

 

High Performance Lubricants https://www.hplubricants.com/

 

GL rated oils, or more correctly the additives in the oil, are exceptionally good at staying in place (protecting) under the twisting loads that are common in an axle. The additives are called Extreme Pressure additives, sulfur is a common one thus the strong sulfur smell gear oils often have.

Take a good look at the ring & pinion gears below, notice the angle of the teeth on the ring gear and also the spiral look of the pinion?



The gears are made that way to give more contact area, it makes the gear stronger (and quieter) than a straight cut gear.
Now visualize how the gear teeth would twist as they meshed and think of the tremendous friction it would create.

Gear oils are compounded to protect against this twisting friction, the additives are designed to stay on the gear, the higher the number the better the protection. For an axle -- so far, so good.




The gears in a manual transmission aren't subject to the twisting forces found in an axle application.

The manual transmission in the Tacoma specifically calls out a GL-4 oil, the reason being that the "better" GL-5 oil is so good at staying on the surfaces it has been discovered that it microscopically rips bits of metal off the brass/bronze synchronizers when shifting causing them to wear out very quickly.

This is called "yellow metal erosion", yes - the oil is "so good" it causes damage.

 

Excellent description of the issue. Thanks for posting this explanation. I have also heard it (sulfur) explained as "corrosive" to the copper and bronze in the manual transmission synchros: actually attacking them and gradually eroding them away over time. Not a problem in the diffs but disastrous to the manual transmission which is otherwise pretty bullet-proof and would outlast all of us.

 

Awesome thread here! I'm getting ready to change my MT transmission and both the from and rear diffs. Would y'all say I am good to go with the following?



Appreciate y'alls help!

 

Yep. Those should do it.
Severe Gear in the Diffs.
MT in the MT.

 

I needed to replace my front CV shafts so I considered it best to replace the differential seals while I rebuilt the complete front end so this causes a need to replace my front differential fluid.

I am reading my copy of the Factory Service Manual for the Gen3 we own and pg. 2142 clearly states that the differential gear oil type and viscosity is to be Toyota LT APL 75W-85 GL-5 or equivalent. APL is a typo and should be API. Locally available equivalent is the synthetic Valvoline 75W-90 API GL-5 and the common qualifying statements regarding meeting/exceeding the API GL-5 are featured in the product labeling. This also states it features the friction modifier for limited slip differentials but I have read reviews of users of the Mobil 1 75W-90 that initially overlooked adding the friction modifier and experienced chattering so they added this promptly and no more undesirable sounds from their LSD.

Have owners found the K&W LSD additive suitable? I can usually buy this locally but will need to order any friction modifier at this time due to no stock.

Ironically, the Toyota Parts website only displays a 75W-140 synthetic gear oil for differentials: https://autoparts.toyota.com/products/product/75w140-gear-oil-quart-0028975140

I anticipate picking up a parts order at my local dealer between Christmas and New Year so I may ask them about why 75W-85 does not appear on the parts website but this could be a simple such as the 75W-85 GL-5 is not available for purchase on the dealer website that features the 10% discount.

I've used RedLine products previously in my Cherokee and they are excellent but I would be hard pressed to purchase products like these (Royal Purple, AMSOil, etc) given their current cost. I would certainly purchase Mobil 1 if were on the shelves locally.

 

I transferred the OEM transfer case can fluid into an empty Valvoline bottle. Filled my transfer case without spilling a drop (except when it overflowed from being full).

 

When I got my truck it was at 29k miles
It looked super clean but you never know who or how they drive it.
I went ahead and did everything at once
T case, and the front and rears with ravenoil
https://www.blauparts.com/toyota-tacoma-transfer-case-differential-fluid-change-kit.html

 

You're more than fine draining and using any quality 75w90 gl5 gear oil in the diffs. LSD additive is not important in ours but if the oil has it, still won't be an issue. Mobil, Valvoline, RedLine, Amsoil are all quality brands. Hell, plenty of people use Super Tech without issues.

While you're doing a drain and fill, consider changing the fill/drain bolts to a hex-style.

 

Way way overthinking it. Not that that’s a bad thing. You can run anything from 75W-85 to 85W-140 GL5/6 without the slightest concern. Ring and pinion gears and bearings do not care.

 

Great info. Thank you

 

I know the front diff has a hex plug, the rear does as well? Planned on ordering the lexus style bolt for the front, didnt realize I needed more than one. About to tackle the diffs next month sometime after changing my MT fluid earlier today..

 

The rear already has hex plugs (external, socket style) so nothing needed there. You just need them for the front. What I have in the picture is comparing the fill/drain of OEM and Lexus male hex.

 

I find 90341-18060 to be a correct part number but 90341-24016 maps to

$13 90341-24014 Front Differential Drain Plug

90341-24014. Can anyone confirm this? The last thing I need to is drive the distance to the dealer and find this is not correct when I try to install it.

Edit - Called the dealer and ordered the -24014 and 90341-18060. I'll take my drain/fill port plugs with the recessed Allen head to the dealer with me to confirm thread pitch/diameter.

 

Confirmed 90341-24016 still comes up correctly; doesn't show a supersession. Keep in mind these are Lexus PNs. Here's where I orders mine from:

https://parts.belllexusnorthscottsdale.com/p/62973757/90341-24016.html

https://parts.belllexusnorthscottsdale.com/p/62973706/90341-18060.html

 

Thanks for this. I called the closest Lexus dealer and they confirmed both. The Toyota label on the drain plug confused me a little. I now have both external hex head front differential plugs secured! Front end rebuild projects are so much fun!

 

For what it's worth, you can get Honda 75W-85 GL-5 gear oil from Amazon --> search "Genuine Honda Hypoid Gear Oil" and it will pop right up. It's not cheap, but it arrived in a day or two, has worked well for front/rear diffs, and was definitely legit packaging. I stick with Toyota OEM for transfer case and use Royal Purple Gear Max (GL-4 / GL-5) for manual transmission.

 

This is good info to know. Not easy to find 85W.

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