Gear oil synthetic or semi

[slides]

Planing on changing the fluids on my diffs and t-case and have read a few thing about synthetics seeping through the seals. How many people run synthetic gear or over semi or conventional.

Price doesn't really mater just more curious about possibly problems and if they come from factory with synthetic gear oil. I currently have 120,000 miles so it's some what young.

 

[gamefreakgc]

Conventional oil here. Stuff like viscosity levels at high or low temperatures don't really matter here like engine oil since these parts don't really heat up. You just want some thick, fresh oil in there.

If your axle seals are going to fail it will regardless of what kind of oil you have in there.

 

[4x4runner2002]

i just did quite a bit of research on this. I've run synthetic and non synthetic oil and I've run a couple different weights as well. I've had a reg open diff, an aussie locked diff, and now i have arb lockers.

i haven't really noticed much difference in performance from synthetic to dino. I also haven't sent my oil to a lab like blackstone to get it tested. But from my most recent findings arb stated in an email to a custom that they run "cheap 80w90 car quest brand oil in their diffs."

they say to use an oil that does not have limited slip additives in a non limited slip diff because it eats o rings. now in an open diff you dont have o rings so that doesn't matter.

I have come to a conclusion to run lucas 80w90 non synthetic in my diffs because i trust their products and they are relatively cheap.

i will also say that i never had leaked due to synthetic oil.
there is lots of great information on different oils on bob is the oil guy forum. check it out and decide for your self.

 

[pluton]

It makes sense to use more expensive synthetic in the gear cases that don't get changed very often. Like Trans, Transfer, and front diff. I change the rear diff oil once a year, so regular 80W-90 is fine for me in that.

 

[slides]

Well I guess I should ask what’s the longest your diff fluid can go without being changed. My fiancé has 2001 rav4 with 185000miles and I’m fairly certain the diffs fluid hasn’t been changed since they bought it.

It’s a sealed system so there is little chance of contamination so if you’re not towing and there isn’t a lot of heat generated couldn’t you theoretically leave it in there for the life of the car.

 

[jgue467]

I've used wallymart's SuperTech full synthetic for about 80,000 miles so far, no leaks. On the rear i went with 75-140, 75-90 on the others. Luck! :cowboy:

 

[ToyotaBrah]

Well I guess I should ask what’s the longest your diff fluid can go without being changed. My fiancé has 2001 rav4 with 185000miles and I’m fairly certain the diffs fluid hasn’t been changed since they bought it.

It’s a sealed system so there is little chance of contamination so if you’re not towing and there isn’t a lot of heat generated couldn’t you theoretically leave it in there for the life of the car.

Gear oils are slightly more resilient than other oils in the car, but they will still degrade. Don't be frugal when it comes to the mechanical side of the car. It will come out to be $10 if you do it yourself or around $35 if you take it to a shop.

 

[slides]

for synthetic mobil 1 its like 11$ a qt and for the front/rear diff & transfer case i think you need 5qts from what i read....oh well fun weekend project.

 

[gamefreakgc]

If you're not sure if you need to change the oil or not, crack open the fill plug (not the drain) and dip your finger in the oil. If you can't get to the oil, your oil level is too low and you need to add more and look to see if you have a leak. It should be clearish like new motor oil. If it's dark or it smells like someone blended up a squirrel, poured it down your axle and let it rot in there for years, then it's time to change the oil.

Seriously though, if you haven't changed gear oil before it smells awful.

 

[ToyotaBrah]

If you're not sure if you need to change the oil or not, crack open the fill plug (not the drain) and dip your finger in the oil. If you can't get to the oil, your oil level is too low and you need to add more and look to see if you have a leak. It should be clearish like new motor oil. If it's dark or it smells like someone blended up a squirrel, poured it down your axle and let it rot in there for years, then it's time to change the oil.

Seriously though, if you haven't changed gear oil before it smells awful.

You mentioned you used conventional oil. What brand do you use and the weight?

 

[gamefreakgc]

You mentioned you used conventional oil. What brand do you use and the weight?

I am using Valvoline 75w-90, but here's a recent conversation about what others are using:

http://www.toyota-4runner.org/3rd-g...l-5-80-90w-limited-slip-gear-oil-my-97-a.html

Basically you can't go wrong with any gear oil.

 

[Lassitor]

Changed front and rear diffs 3 weeks ago. Used 75w-90 Mobil1 synth. No problems yet, but it really hasn't been that long either. Get new gaskets/crush gaskets!

 

[pluton]

I feel the rear diff is very hard working oil, so I change it more often.
Trans and transfer are easy on oil. I'm convinced that MT-90 will last 60,000 miles in trans/transfer.

 

[19963.4lsr5]

I put 75w140 synthetic in the rear and a 75w90 semi synthetic in the front and t-case

 

[pluton]

I tried the 75W-140 Mobil 1 in my old '91 4WD truck's rear diff, and I found that it made the [4cyl]truck slower on the highway!

 

[slides]

Pick up Mobil 1 75w90 synthetic and swapped out the rear diff and t-case. The rear diff was nasty with some gray stuff mixed in idk could have been water or something. Anyhow the front diff I couldn't break the Hex's free so picking up ac adaptedatef and tackle it tomorrow.