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

Prior trucks fluid was just dark and no more thick, or thin, than you would expect 75W gear oil to be. In the '21 it literally looked like (relatively) clean 75w gear oil. Just interesting to see such a difference.

 

If it's dark and not extra sludgy that's just breaking coating wearing off. Although it is interesting that your new one doesn't have that in there. Then again I have no idea because some of the trucks we service are exactly the same. After 60,000 miles, the fluid comes out looking brand new and other trucks we service at similar mileage The fluid comes out very dark like you describe.

 

Are people using this plug on transfer case, manual transmission or ………..? I changed all the fluids at 4,500 miles and the differential fluids looked nasty. I used the motorcraft in the transmission and amsoil in front and rear diff. This time around I went redline on everything and feel like I wasted good oil since everything looked pretty clear and nothing crazy on the magnets. All fluids had 15k miles on them. I think I’ll wait until I’m at 50k for the next change. That’ll be 30k miles on the redline fluids I just put in and should take me over 2 years to put those miles on the truck.

By the way, thank you OP for the great thread with all the details.

 

Nasty as in thick like sludge? Or dark and runny?

Yeah you're definitely changing them at tiny intervals. Should have no problem going 50k

 

It looked thick to me and black as it could be. Definitely going 30k miles this time around.

 

Black on the first change is normal, just break in material. That being said, some people's first change (like my rear at 55k) the oil looked damn near perfect

 

Yeah, first drain results seem to be all over the place. The only towing I’ve done is a small uhaul trailer to the landfill 7 miles away twice, so I have not put it to work. I noticed the maintenance booklet said to change the differential fluid at 15k miles under “special conditions” so figured I would start there and adjust intervals depending on the condition of the fluid. I feel better now going longer.
As for the transmission, the first 4500 miles on stock oil were not fun. I put the ford oil in and made a significant improvement but 2nd and 3rd were still a little “crunchy”. The ford juice came out looking like honey At 15k miles and the redline went in. Just drove it 20 miles and feel a slight improvement (might just be in my head) but I’ll give it some time and then decide if redline is better than the ford stuff.

 

To be fair, Redline is magic.

 

I would agree. DP runs Redline everywhere except Castrol in the engine.

 

Yeah but.... Is it 10W-40?

 

So I know the old saying is don’t change transmission fluid if you’ve not done it and you’re high mileage, blah blah blah.

My 2017 is about to hit 100k and I want to change the manual transmission fluid to see if the shifting gets smoother. Opinions as to if this could be a bad idea?

 

Manual transmission fluid is just gear oil. You'll be just fine

 

That is generally a saying for ATs. There, I would agree to stick with whatever was established. Currently puckering to see what happens with our 90k Subaru.

For MTs, disregard that nugget.

 

That old saying is dumb. Change them both at 60k. If they're clean, wait another 60. If they're dirty (cause you use your truck hard etc) change them again at 100k.

 

Going for all fluid change today! Along with plugs and filters

 

Which washer fluid you using? Gonna bleed brakes too? Recommended every 2-3 years to prevent moisture buildup (although Toyota Master cylinder seals are the best on the market). And use the Toyota sllc pink coolant if you can. Best stuff ever made.






I figured oil and gear oil and differential oil have been covered enough in these threads

 

Damn it’s low on washer fluid! Good catch. Just did front and rear diff and trans and motor oil. Took 2.5 hours not knowing what I was doing besides reading here

 

I mean if you're going to be doing the differentials and the transmission, you may as well do the transfer case while you're under there

 

I made my own.

https://www.tacomaworld.com/threads...-plug-part-number.655172/page-2#post-27224816

 

Damn inflation, I bought a gallon of Redline MT-90 to change the 5MT fluid on my 2nd gen, Oct 2, $69 on Amazon. Today Dec 16, $82.50.