Diff and Transfer Case fluid recommendations

Sure, they do. Not disagreeing. But with the oil analysis I've seen posted and done on my own, there's no leg up they have on anything less expensive so long as you don't neglect doing the services. People are free to spend their money on what they want for their rigs. But the thought that Amsoil is some super fluid hands above the rest is just incorrect

 

Amsoil all the way for me. Diffs, Transfer, engine. Everything except of the Transmission

 

Lol

 

I have a pile of these for my front and rear diffs at the moment. I trust it will be just fine.
I did bite the expensive bullet and bought 75W Ravenol for the transfer case. Ehhhh.

 

agreed here. Dont use diff gear oil in the TC, it not good on the brass synchros.

 

The Car Care Nut says no adverse effects from using 75-90 GL-5 in Transfer Case and it is specified for improved mileage only. The owner’s manual does specify straight 75 gear oil. 2 Toyota Dealers near me use the 75-90 GL-5 in all transfer cases they service. Both don’t sell the 75 weight oil. Is there some reference about brass synchros? Is there some additive in the 75-90 that is incompatible ?

 

This only matters with manual transmission synchros.

 

Really? Because in my truck with the manual shift lever when I shift into 4H at say, 35-40 MPH I can hear the synchros doing what they do.

 

Check out this post below.

https://www.4runners.com/threads/re...er-case-oils-a-good-alternative-to-oem.29867/

 

Synchros don’t make noise. What you hear is the shift into 4wd and it will be louder under load.

 

Yup. Synchro materials are soft. They allow a smooth transition between gears. If you don't have syncros, you'd have to find every gate pretty much perfect and your shifting would be very notchy. This is the reason in old rigs that you float shift and/or rev match (manuals). When your syncros wear out, shifting becomes much more difficult

 

Toyota dealers don’t even use Toyota 75W LF gear oil. They use the cheapest 75w90 bulk gear oil they can get

 

i believe ive read several times that the GL 5 is too harsh on the brass synchros. Ive only used Redline MT-LV in my TCs.

Regular synthetic gear oil (Mobil 1 etc.) is not recommended because of high phosphate levels that may damage the soft metal (copper, brass) in the transfer case synchros.

 

Thats why you gotta do this stuff yourself. You cant trust anyone anymore to put quality stuff in your 4RNR but yourself.

 

that is incorrect. Its just not in manual trans only

 

Is the

is the Redline MT-LV ok for 4 Runner TC? The owners manual doesn’t specify GL-5 or GL-4? Odd? Even the Toyota LT 75 is not specified as GL-5 or GL-4.

 

I picked this gear oil up at dealer yesterday for 4 Runner diffs. It is distributed by Southeast Toyota and is what they use for service. It is 75-90, GL-5. It is NOT a Toyota branded oil.

 

Manuals have synchros, our transfer cases do not. You guys just like to make things more complicated for no reason. Toyota doesn’t make oil.

 

yes the Redline in fine. Used it in 2011 3 times in the TC and had 164k on it

 

im not making it complicated, its just what i read several times.

 

I find it odd that the Owner’s Manual does not list the GL number for the TC gear oil. But GL-5 is listed for the front and rear differentials

 

and the reason why it doesnt is because that stuff is too harsh for TC internals

 

So if you use Redline MT-LV labeled as GL-4, it would be nice to know it meets the GL spec for the 4 Runner. But since Manual doesn’t list it, you can’t be sure. I have not seen a GL number associated with the LF 75 gear oil specified for the Transfer case in 4 Runner owner Manual

 

Heres some pics of my bottle

 

Nice! I did not know the bottle specifically listed Toyota LF 75 W.

 

Um, yes, they do. I have driven manual transmissions for decades, and on a downshift, all manual transmissions spin up to make the gears mesh easily. I know what the sound is that I am hearing, it is the spin up of the transfer case to make the rpm equal enough to allow the gears to engage without crashing.

My 4H won't engage without removing the load, in other words, taking my foot off the accelerator to remove the load.

 

This is absolutely incorrect. The syncros do not make noise... Unless there is something wrong with them. Once you are in or out of gear the syncros are completely out of the picture.

 

Okay, let me simplify this for you. The transfer case RPMS increase when the vehicle is moving and the manual shifter is moved into 4H. I can hear the sound of the RPMs increase when traveling at speeds over 30 MPH when shifting. Just the same as when I was downshifting in all of my other manual transmission cars. For you hair splitters, the synchros are doing their job, and okay, it is not the synchros I am hearing. Happy now?

 

yep, made the purchase a no brainer.

 

I drove a manual Ranger for 5 years and now have a manual GTO. You may hear gear whine when there’s a load but the synchros themselves don’t make noise.

Transmission gears are in constant mesh. The synchros are there to match the shift collar to new gear speed. If you hear anything it’s because it’s bad.

I once had an officer tell me he could hear my aftermarket pistons and cams…of my 93 RX7. Sounds like I’m there again.

Yes, normal for the shift to go in easier when you take the load away.