Synthetic Gear-Oil for Diff - Question

M

michael90630

New member
I have reviewed a few posts here regarding this topic of using synthetic gear-oils in the front and rear differentials and the transfer case.

I am planning to go with Amsoil Synthetic 7W-90 gear oil however just wanted to confirm a few things:

1) Is it better to go with the regular Amsoil 75W-90 or the Amsoil Severe 75W-90 gear oil? I believe the Severe one is rated at GL-5 instead of GL-4. In the 4Runner, what is the recommended one - GL-4 or GL-5? It is not recommended to use a GL-5 on a GL-4 application because of the additives.

2) Has anyone used this synthetic in the transfer case? Does it attack any rubber seals? In my last two attempts to use Synthetic gear-oils on my Nissan Maxima trans-axle, both time it started to leak. So I am a bit skeptical about using synthetic in a trans-axle or transfer case.

3) How many quarts are needed to re-fill the transfer-case?

Thanks
 
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I put in the Severe 75-90 when almost new (30k miles so far) and everything is fine.

Koz
 
Synthetics are a waste of money in a simple gearset like a rear differential. There are lots of articles on this on the Web, and some big name 4x4 axle makers will even void your warranty if you use synthetics in their axles. Gears don't need the special properties of syn oil they just need to stay cool. Because of the properties of synthetic oil, it can actually shorten the life of your gears. I personally have had problems with syn oil in a rear diff before and when I switched back to $3/quart Walmart oil it started running smooth as butter again. My advice is to save your money and get regular oil. Don't buy into the hype.

As far as the t-case...I would use exactly what Toyota recommends in that case because you've got a lot of moving parts in there and it's a different animal.
 
WXman said:
Synthetics are a waste of money in a simple gearset like a rear differential. There are lots of articles on this on the Web, and some big name 4x4 axle makers will even void your warranty if you use synthetics in their axles. Gears don't need the special properties of syn oil they just need to stay cool. Because of the properties of synthetic oil, it can actually shorten the life of your gears. I personally have had problems with syn oil in a rear diff before and when I switched back to $3/quart Walmart oil it started running smooth as butter again. My advice is to save your money and get regular oil. Don't buy into the hype.

As far as the t-case...I would use exactly what Toyota recommends in that case because you've got a lot of moving parts in there and it's a different animal.
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NEVER EVER heard this. Are you able to share links to these articles and reports so we can read up?
 
xxaarraa said:
NEVER EVER heard this. Are you able to share links to these articles and reports so we can read up?
Click to expand...

Call Dynatrac and talk to Scott. Call ARB. Call Auburn Gear. The people in the 4x4 industry who really know axles will all tell you to use regular 80W90 gear oil, and if you tow you should use regular 80W140 gear oil. The guys who build axles day in and day out for abuse do NOT recommend synthetic oils. This is especially true if you have an axle that requires friction additives for a limited slip unit.

RCs4Runner said:
Of course not. As the Brits say, he's talking out of his arse.

Both Lexus and Toyota use synthetic gear oils.
TSB DL003-07
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I keep forgetting that this isn't a Jeep forum, and some people here aren't very mechanically inclined. It's all internet "hearsay". My bad. :baby: Would it help you if I drew a picture in crayon to explain why you're wasting your money by using a syn oil in a simple gearset? Remember, the people who wrote that link you posted are the same people who said the transmission fluid in our vehicles is good "for life". Lol.
 
WXman said:
Call Dynatrac and talk to Scott. Call ARB. Call Auburn Gear. The people in the 4x4 industry who really know axles will all tell you to use regular 80W90 gear oil, and if you tow you should use regular 80W140 gear oil. The guys who build axles day in and day out for abuse do NOT recommend synthetic oils. This is especially true if you have an axle that requires friction additives for a limited slip unit.


I keep forgetting that this isn't a Jeep forum, and some people here aren't very mechanically inclined. It's all internet "hearsay". My bad. :baby: Would it help you if I drew a picture in crayon to explain why you're wasting your money by using a syn oil in a simple gearset? Remember, the people who wrote that link you posted are the same people who said the transmission fluid in our vehicles is good "for life". Lol.
Click to expand...

How about you link us to all the articles and literature you said is available to support your theory?

When you say pretty outrageously funny things like this, you gotta back it up with more than just insults. "There are lots of articles on this on the Web, and some big name 4x4 axle makers will even void your warranty if you use synthetics in their axles."

You need to make up your mind. You recommended above to use "exactly what Toyota recommends" and then you contradict yourself immediately.
 
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WXman said:
I keep forgetting that this isn't a Jeep forum, and some people here aren't very mechanically inclined. It's all internet "hearsay". My bad. :baby: Would it help you if I drew a picture in crayon to explain why you're wasting your money by using a syn oil in a simple gearset? Remember, the people who wrote that link you posted are the same people who said the transmission fluid in our vehicles is good "for life". Lol.
Click to expand...

I must've missed all of the blown diff threads since Toyota / Lexus switched to synthetic gear oils. :dizzy:

I guess you're one of those "aren't very mechanically inclined" people you're speaking about seeing as you yourself used synthetic gear oil in your rear diff. And wow, it sounds like you have some serious mechanically skills too w/ your "airbox mod".


xxaarraa said:
You need to make up your mind. You recommended above to use "exactly what Toyota recommends" and then you contradict yourself immediately.
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Like I said, he talks out of his azz.
 
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WXman said:
Call Dynatrac and talk to Scott. Call ARB. Call Auburn Gear. The people in the 4x4 industry who really know axles will all tell you to use regular 80W90 gear oil, and if you tow you should use regular 80W140 gear oil. The guys who build axles day in and day out for abuse do NOT recommend synthetic oils. This is especially true if you have an axle that requires friction additives for a limited slip unit.




I keep forgetting that this isn't a Jeep forum, and some people here aren't very mechanically inclined. It's all internet "hearsay". My bad. :baby: Would it help you if I drew a picture in crayon to explain why you're wasting your money by using a syn oil in a simple gearset? Remember, the people who wrote that link you posted are the same people who said the transmission fluid in our vehicles is good "for life". Lol.
Click to expand...


Whoa... there are some really top notch mechanics here on the forum. Many guys and gals who've been around 4 x 4's for MANY years!

I've used synthetics in ALL my 4 x 4 drivelines for twenty plus years! Currently run Redline in my front and rear diffs and transfer case.

Synthetics... especially an Amsoil Severe or a Redline and even Mobil Synthetic... highly recommended for both diffs!
 
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