3rd Gen Differential and Manual Transmission (6MT) Fluid Change

WARNING THIS IS LONG AF.

tl;dr - I do not hoon this truck. I followed the recommended break-in procedure to a t and drive relatively conservatively every day. That said, seriously consider checking/replacing your diff fluids early. I would not wait until the service interval. I'll update more when I get the Blackstone Labs results, but those fluids were in rough shape (all 3 fluid samples will be sent to Blackstone).


So I searched high and low both here and on other forums and noticed the procedure hasn't really been documented in detail (brief steps in the maintenance sticky up top, but generally people just saying they did the work). I wanted to do a write up that documented the procedure in detail and with pictures so others looking to do the same would have a reference. I also wanted to detail the front diff and manual transmission procedure as those really aren't documented. The rear is pretty self-explanatory. So lets get to it!

Background

My 2016 TRD Sport (DCSB), 6M/T has just over 10,500 miles on it. It recently has had its first oil change, and for the most part has been stellar. I do have a few of the 3rd gen bugs, most annoying of which is the diff howl. I say this about most of my vehicles, but I intend on keeping this truck until it's driven into the ground or it rusts out (or I finally succumb to the allure of the 200 series LC); in any case, I like taking care of my things, especially the expensive ones. I don't expect this to fix the diff howl, but after seeing what came out, I'm glad I did it now rather than later.

The truck went in for it's 10k service and oil change a few weeks ago and after seeing a few posts on here about the condition of the other fluids, I decided I'd bite the bullet and do the service. This service is NOT cheap from a dealer so a friend and I tackled it ourselves in my driveway. I would have included a transfer case fluid change as well, but Toyota specifies their proprietary 75w LF gear oil, for which I could not find a suitable equivalent.

I paid for the 2 day subscription for TIS to confirm bolt torques and locations but this was not necessary with the stickies maintenance thread linked again (so if anyone needs anything between now and Tuesday...) - https://www.tacomaworld.com/threads/3rd-gen-diy-maintenance-quick-reference.406712/

Parts List

• 6 quarts 75w-85 GL-5 or equivalent gear oil (more or less depending on your model) - I used Amsoil 75w-90 Severe Gear
• 
  
• 3 quarts 75w-90 GL-3 (GL-4) Manual Transmission fluid - used Amsoil 75w-90 Manual Transmission Gear Lube
• 
  
• Gasket Set (
  $14 GENUINE TOYOTA GASKET KIT FOR TRANSFER AND DIFFERENTIAL SERVICE
  https://www.amazon.com/gp/product/B017V4BAXI/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1) - this kit works perfectly since the transfer case uses the same "gaskets" as the transmission and I didn't touch that fluid
• Oil pump - something like this but hopefully yours isn't as crappy:
  $10 Plews 55001 Lubrimatic Fluid Quart Pump, Fits Standard Quart Bottles
  https://www.amazon.com/gp/product/B000BQW5LK/ref=oh_aui_detailpage_o03_s01?ie=UTF8&psc=1
• Drain pan
• Torque Wrench (minimum torque value 20 lb-ft)
• Breaker bar/regular socket wrench (DO NOT loosen bolts with your torque wrench)
• 24 mm socket (not required but a thin walled, shallow socket would be ideal)
• 10 mm hex socket

Optional:

• Beer - because any wrenching requires it at my house. I chose Deschutes Brewery's Pacific Wonderland Lager.
• Test Sample Kits from Blackstone Labs. It's my way of understanding what's going on for the fluids and also a third party way of documenting what was going on in the future.
• A nice jack and jack stands - keeping the driver side front wheel off for the front diff change made life much easier. Just make sure everything is level!
• Creeper or cardboard
• Kitty litter or something for spills
• Nitrile gloves
• Drive around a mile or two to warm up the fluids and suspend and particulates in the fluid, wait for the exhaust to cool before you begin.

Procedure & Notes

A general note first, this is essentially the same procedure for the diffs and trans and it goes as follows:

• Remove the fill plug first - there are a few reasons for this, but one is in case you find out your drain plug is stuck. You won't be stranded this way. Second is to provide some air outlet for the draining part. The fluid will come out much smoother and make a lot less mess.
• You know you're done filling the part when the fluid begins to trickle out (if you're level). Per the FSM, the fill level is 0 to 5mm from the bottom of the fill plug hole. The other way is to measure exactly what you're putting in vs. Toyota's requirements, which is just more work.
• 

Transmission first!

• Locate the drain and fill bolts on the manual transmission. These can be accessed from the passenger side of the truck.
• 
  
• Using your breaker bar and 24mm socket, loosen fill plug first, this is where the shallow socket is key. The fill plug has about 2" of space between it and the O2 sensor near the cat. I removed the fill plug and checked the fluid level (close enough to full for me). Full for all of the following is 0 to 5mm from the bottom opening of the fill plug hole.
• Get your drain pan under the drain hole but with space for the fluid to shoot forward a bit.
• Loosen the drain plug the same as the fill plug. Once the bolt is loose, remove by hand and expect the transmission fluid to come out with some force. In my case I had my Blackstone sample bottle ready to collect before letting the rest drain into the pan. The fluid coming out was almost like a light maple syrup color, which is close to what I would expect. Keep in mind the new fluid looks similar to canola oil (in color).
• 
  
• Once the trickle stops, wipe everything down and replace the drain plug. Be sure to use a new flat washer provided in the gasket kit. Torque to 27 lb-ft.
• Using your pump, pump in your new MT fluid. In my case, I needed just a bit over 2.6 quarts which is what the service manual calls for, using the fill specification noted above (0 to 5mm from the bottom of the fill hole).
• Using another new flat washer from the kit, replace the fill plug and torque to 27 lb-ft. Make sure you have the old washers removed!
• Wipe everything down of excess oil. You'll want this to be clean so not to attract dirt, but also to check for leaks later.

Front diff:

• Locate the drain and fill bolts for the front differential. These will be accessed from the driver's side of the truck. The CV axle going into your wheel will come directly from the diff. For the sake of access, removing the driver front wheel made this task much easier.
• 
  
• Using your breaker bar and 10mm hex socket, loosen then remove the fill plug.
• Get your drain pan under the drain hole, again with space for the fluid to shoot forward (though this really didn't have much pressure behind it).
• Loosen the drain plug the same as the fill plug. This plug is magnetic and had a decent amount of crud on it. Again, I collected my Blackstone sample and let the fluid drain. This fluid was WAY darker than I expected and full of glitter. This was somewhat alarming to me as my front diff isn't used all that often. I try to get my 10 miles a month in 4wd to keep everything lubricated and it had some longer term use during the one big snow last winter; this was worse than when I did the same service on my 4Runner which was full time 4wd.
• 
  
• Clean all the gunk off the drain plug.
• Once the trickle stops, wipe everything down and replace the drain plug. Take note this plug uses the copper washer provided in the gasket kit; remove the old, replace with the new. Torque to 48 lb-ft.
• Using your pump, pump in your new diff fluid. I used just a bit under 1.6 quarts.
• Using a crush washer from your gasket kit, replace the fill plug and torque to 29 lb-ft.
• Wipe everything down of excess oil.

Rear diff:

• Locate the drain and fill bolts for the rear differential. These will be accessed from the rear of the truck. I chose to drop the spare for more space and I'm glad I did. (note: your drain plug may be on the driver side depending on the diff; the larger diffs on the manuals and TRDORs will be on the passenger side)
• 
  
• Using your breaker bar and 24mm socket, loosen then remove the fill plug.
• Get your drain pan under the drain hole.
• Loosen the drain plug. This is where a thin walled socket helps. I have no idea what they torqued it to from the factory but it was a b**** to get loose. Remove by hand and wait for the flood of black fluid. Again the plug is magnetic and CAKED with a thick later of sludge. Clean it all off and pat yourself on the back for doing this now and not later.
• 
  
• Once the trickle stops, wipe everything down and replace the drain plug. Discard the old crush washer and use a new one from the kit. Torque to 36 lb-ft.
• 
  
• Using your pump, pump in your new diff fluid until full. I used just over 4.3 quarts.
• Using the last new crush washer from your gasket kit, replace the fill plug and torque to 36 lb-ft.
• Wipe everything off!

You're done!

Drink another beer and clean up. Technically you should drive around a bit and re-check fluid levels. I'm confident that what came out was replaced so I won't be doing this. I will, however, check the drain and fill bolts tomorrow after my commute to ensure there aren't any leaks.

I am a bit alarmed at the quality of the diff fluid coming out of the truck after only 10k miles. I'll hold my tongue until I get the Blackstone results back (the samples will be shipped sometime this week). I'll update the thread accordingly.


Update 1: [3/21/17] Blackstone samples sent via UPS. Will update again with result sheets. 3 samples were sent, 1 for the front diff, 1 for the MT fluid, 1 for the rear diff.

Update 2: [3/25/17] Blackstone results are IN! Here are my comments and the result sheets: https://www.tacomaworld.com/threads...-6mt-fluid-change.481719/page-4#post-14749797

Update 3: [10/19/18] Blackstone samples sent via USPS (arrived to Blackstone Labs on 10/29). Amsoil fluids after 20k miles appears in sample containers here: 3rd Gen Differential and Manual Transmission (6MT) Fluid Change

Update 4: [11/04/18] Blackstone results are IN! USPS lost the Front Diff sample (bastards!). https://www.tacomaworld.com/threads...6mt-fluid-change.481719/page-17#post-19064948. Edit 11/29/18, front diff fluid delivered to Blackstone and tested!

OA

 

Nice job
Subbed for blackstone results

 

This is quality stuff OP.

Good job.

 

Nice write up and nice work, just curious if the Rear Diff has any less noise after the change?

 

Awesome walkthrough, looks like you've done one of these before. A few things you might want to clarify for thoroughness.

1) Really emphasize, open fill plugs first
2) How do I know when I've put enough new oil in?
3) That pump really, really, really sucks, I think I cried last time I used it.

 

Just ordered the gasket set. Following for results. My 17 is 3,000 away from the 10,000. Does the manual suggest to change all fluid at 10K?

 

So my diff only howled when feathering the throttle around 55-60mph. After the work I didn't have an opportunity to get up to that speed. I will say the truck as a whole operated much smoother than before but I regreased my zerks as well so it's hard to attribute it to just one thing yet. I'll update after my commute tomorrow.

Good call, I appreciate the feedback. I'll make those changes now!

OA

 

I don't have it in front of me but the only fluid that is to be changed at 10k per the manual (under normal operating conditions) is the engine oil. The diffs and trans don't come up till MUCH later.

OA

 

Awesome job!

 

Nice post. Sub'd for results. I'm gonna go ahead and predict that blackstone says everything looks as expected for break in fluids though.

 

Nice OP. Any concern using 75-90 instead of 75-85?

 

Good call and I somewhat expect the same. The issue is these fluids wouldn't be serviced for some time under Toyota's maintenance interval. When in reality they should probably be dumped as part of break-in.

OA

 

Honestly no. The delta has to be pretty small in actual use conditions. If anything it might have a bit more resistance as it's slightly thicker but I doubt it will be noticeable. ECGS, who is really well known in this business recommends 75w-140 for the Toyota diffs they work on; I think they're just less gas efficient. I'll update over the next few weeks if I notice changes.

OA

 

I agree. Good job.

ECGS recommends 85w-140 by the way. If you order it from them they send Lucas brand in that weight but I'm sure other brands would work too.

 

Man your fluid came out pretty dark. I did mine right at 5K, and the drained fluid didn't look bad at all. My drain plug magnets were dirty, but not that caked up fortunately. How many miles are on your truck?

 

Sub'd for results

This needs to be added to a reference point *sticky* or within a *sticky*

Well done!

 

I did my mt fluid at 17k. Didn't see any reason to use new washers. Is it even necessary?

 

I'm on my third rear differential, so im not sure if I need to do this yet. Maybe I'll wait for the next replacement.

 

Sub'd

Checked my diff fluid today and it looked ok. Only 3k. But I'm not against changing the fluid at my next oils change.

Great write up!

 

Great write up! I'm looking to do exactly this with mine in 5k or so. Thanks for making it much easier.