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

One more to the list, done mine on Saturday.
Found rear diff low 1 qt and replaced with 4.4 qt (pumped till is was coming out in continuous flow, I wasted a bit of oil but made sure is full).
Front diff was filled OK and looked pretty clean. Pumped the rest of oil in (1.6 qt) till it was flowing out steady. Still have left about 1/2 in at the bottom of the 6th bottle. Also replaced the engine oil and filter.
Used AMSoil 0W-20 and 5W-30 mixed 50/50 and AMSoil

$29 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90 for diffs. OEM for oil filter.
Found cabin air filter pretty dirty and replaced it with FRAM type with febreze...

 

Why mix oil weight?

I am under the impression that mixing weight is a bad idea.

Although I run a quart of Lucus oil and fill the rest with regular oil in my older pickup. Works pretty good in that application.

 

I checked all of my levels today (2017 TRD Sport MT with 4k miles) and everything was full except tranny. Had to add 21 ozs, which is about 25% LOW. Wow! What kind of a record of this should I keep in case of warranty issues with the MT? I think I'm gonna completely change out the tranny oil today. This couldn't be good to be this low!

 

That’s pretty low for a trans but if it’s driving fine then don’t fret too much about it. You caught it relatively early which is a good thing. To be honest I’m not sure there is much you can do as far as documenting since you’ve already added the oil.

I sent mine out for testing for the sake of knowledge, but it’s possibly a good way to see what, if anything, happened internally.

OA

 

Update: I changed out my trans oil after finding it 25% low (and after adding 21 oz to top it off). It was dark, with sparkles in it. Nothing stuck on the drain plug. Is the drain plug in the tranny magnetic? I saved the old oil so I can get it tested OR take it to the dealer at my 5k "check up"....or BOTH!

 

Transmission drain plug is not magnetic.

OA

 

Oops, I moved too quickly and changed out my MT fluid with GL-5 (of course the bottle says GL-4 compatible), but now I'm reading all kinds of info that says don't use that in the tranny. The problem is finding GL-4 in the right viscosity in my local area. I found 85w-90, but as you all know, it is spec'd to be

$29 75w-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75w-90. Is it a bad idea to use 85w-90? It gets down to temps of zero sometimes during the winter here, but generally cold spells hover around 20s.

Also wondering if I need to pull that GL-5 soon or can it wait a week until I can get some proper GL-4 75w-90? It's driving fine, shifting better than before.

 

$91 Red Line 50305 MT-90 75W-90 GL-4 Manual Transmission and Transaxle Lubricant (MTL) - 1 Gallon

https://www.amazon.com/Red-Line-503...dline+75w-90+Manual+Transmission+Fluid+gallon

 

If it were me, I'd be afraid the potentially high sulfur content of the GL-5 could eat away soft metals in the MT. Not 911, but I'd get some and change out your next day off.

FWIW, This Motorcraft stuff has good reviews on-line, is 100% synth. and GL-4 (Supposedly 75w80)

• Manual trans fluid:$21 Genuine Ford Fluid XT-M5-QS Full Synthetic Manual Transmission Fluid - 1 Quart 3 of Genuine Ford Fluid XT-M5-QS Full Synthetic Manual Transmission Fluid - 1 Quart

 

Update: I finally got my tranny filled with Redline

$29 75w-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75w-90 G-4. Wow, what a difference! Far better shifting than when the tranny was low and slight but noticeable better shifting from when it was filled with G-5 for about a week. Made a believer out of me!

 

Another update: I changed out my diffs today with the truck at 4800 miles. Oil and drain plugs were in the same shape as pictured in OP. Filled with Redline 75w-85 and all is well. Between rear and front it took 6+ quarts. Should have taken 5.6 quarts total (4 rear, 1.6 front) so I'm not sure why that is. I have the MT version and nothin special about the rear diff.

 

Getting ready to do this this weekend I’m at 38k on Mine. Do I have to jack the truck up or can I just crawl underneath and do everything?

 

Shouldn’t need to jack the truck up as when you fill you want the vehicle level to get the appropriate amount

 

@Fortunt1 is right - you are going to want the truck totally level to do it. That said, drop your spare for access to the rear diff. I also removed the driver side front wheel and lowered it to level for access to the front diff.

Both steps probably aren’t necessary but they make life much easier.

OA

 

I need to buy front diff oil to change it
Kind of confused here between what’s GL-4 and GL-5.
I see some used Amsoil and others used Redline.
Are people not using Toyota 75w-85 oil bc it’s more expensive/availability/quality or simply their choice?

SN: OP @Omar RVA you’re in RVA same here

 

You should use GL-5 for the differentials. Toyota specs the option for GL-3 or GL-4 for the manual transmission.

The Toyota gear oil is probably good, but I used

$29 75w-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75w-90 because it’s more more readily available and Amsoil offers better performance characteristics (though in all likelyhood, my truck isn’t extreme enough to realize much difference). Anecdotal evidence also suggests many dealers don’t even bother with Toyota gear oils and just buy bulk drums of equivalent oil that would work (Mobile 75w-90 seems to be common.

[edited last paragraph since you’re clearly aware of the RVA group haha] Glad to see another RVAer around!

OA

 

Looking to do this over the weekend as my rig just ticked over 10k miles. Any suggestions for a better quality manual oil pump for this project? Google search really didn't turn up anything. Like OP mentioned, the one he listed looks pretty flimsy.

Thanks all!

 

I second the Ford Motorcraft oil. Started out with the OEM fluid, changed to Redline. Big improvement, but the oil is really thick at cold temps and makes shifting sluggish. Switched to Amsoil. BIG MISTAKE. Maybe this stuff is OK in other MT's, but it really sucks in the 17 6MT. Too thin, lots of grinding. Mechanic I have talked to, a performance car enthusiast, says Amsoil is bad. He says redline is good stuff.

The Ford stuff is like magic, get it if you can, Redline is good stuff but I think people in colder climates will be disappointed with its performance. Really improved shifting into reverse after installing the URD short throw kit.

 

Thanks for posting this. I'm close to 6k and was thinking about doing the diffs based on other posts. I appreciate that you posted the torques and quantities all in one spot, and your UOA analysis has me planning on doing the transmission also.

 

I'm not really trying to contribute to an oil debate, just wanting to state something from experience. The Reline MT oil was the only thing that helped out our old saab MT. Many others felt the same. It was an incredible difference, even after trying two other fluids including the OEM, which required flushes since they were incompatible.