Synthetic or non synthetic gear oil? whats everyone running?

[dedonderosa]

have been debating on what i want to use in my front and rear diff. i have been searching around and wanted to see what everyone is running in their front and rear diffs ? been seeing mixed reviews with people saying use synthetic 75w90 and many others saying stay away from synthetic gear but not sure exactly why. let me know you opinions and what you using etc. thank you guys

 

[chester4Run]

I've been using Amsoil 75w90 for the last 60K miles. I just changed both front and rear and the oil appeared as new in both after that mileage. The argument I've heard for conventional oil is better heat dissipation. I haven't checked the differential temps on my 4Runner, but years ago when I started using synthetic gear oil in my Jeep I did do so. (checked when arrived home, at highway rest-stops, after wheeling, all of this in sunny, warm, FL) The differential casing was always within a couple degrees of the frame temperature.

 

[<<<<]

Red Line 75w-85 GL-5 because that is the weight Toyota recommends for this truck. Few other companies make 75w-85 though.

 

[epjfsa]

Anyone who says stay away from synthetic probably still says that [any established technology] in cars is just "one more thing to break." It's 2019, use synthetic. I'm using Amsoil as well.

 

[MTN4RNR]

I opt for Redline 75w85. One of the only options that stays within Toyota spec. Lots of people use 75w-90 with no issues. In either case, go with a synthetic... /thread

 

[STX4Runner]

Redline 75 85 as well. Had it in the rear for the last 60,000 miles and just changed the front last year and put it in.

 

[Jetboy]

Amazon has Toyota OEM oil "Used, Like New" for $23/qt. What do you think "used, like new" means? lol.

I still have whatever Toyota put in originally. I'll probably swap out to a synthetic of the same weight. I'm not totally sure the original is not synthetic, but I don't know. I haven't found much information on what it actually is.

 

[Lester Lugnut]

I wonder if this "use only conventional gear oil" thing is the result of the following article by East Coast Gear Supply?

https://eastcoastgearsupply.com/files/PDF Files/ecgs-gear-oil-recommendation1.pdf

Early on they mentioned "clutch". OK - maybe for that type of application, but how many 4 Runners / Tacoma's / etc - have this today?

Mine is a 2WD. Have been running Super-Tech 75W-90 full synthetic and see none of the problems brought up on the web.

 

[catrains]

the 4 runner has open diff's so NO clutches .. my GM sedan has a posi traction full time rear diff so I have to use conventional gear oil with the slip additive because it has clutch .. so synthetic on my GM sedan will not work properly get chatter ..

Toyota runner open diff I asked the dealership . they said 75-90wt synthetic , suck it out from 55 gallon drums ..

I changed my rear diff @3K miles because of a heat damage on the oil.gray and particles in it .. so far now 20K miles on the mobil synthetic 75-90wt oil looks like new . I also increased MPG by 2 ..

I will use the toyota transfer case oil very specific has many lube additives . not an issue on the 75WT the issue is the lubrication additives .. expensive odd ball fluid 30K-40K miles replacing use..

 

[enyce]

Amsoil Synthetic 75W-90 for the rear diff.

 

[QwikKotaTx]

Don't overthink it. There are millions of trucks on the road with 100k miles and the owner has never changed the diff fluid. 60k should be fine on the OEM fluid.

 

[zonzin]

Mobile 1 75/90 F&R diffs, Royal Purple Synchromax Transfr.
Comes out looking clean every 30k.


.

 

[QwikKotaTx]

Mobile 1 75/90 F&R diffs, Royal Purple Synchromax Transfr.
Comes out looking clean every 30k.


.

Then why do you change it so often?

 

[Gclark949]

Amsoil. Both front and rear Toyota oil came out surprisingly dirty looking at 10,000 miles so I was glad I spent the money but I am sure most of that is just new gears wearing in and would not normally look so bad after so few miles.

 

[dedonderosa]

Mobile 1 75/90 F&R diffs, Royal Purple Synchromax Transfr.
Comes out looking clean every 30k.


.

isnt the transfer case suppose to use "toyota 75w" as there are a ton of additives in this fluid compared to other fluid people are using

 

[IanB]

If you're doing a lot of water crossings you should be changing your diff fluids frequently, I'd use non-synthetic in this scenario. If you're planning on changing them and then leaving them like that for years, use synthetic.

 

[zonzin]

Then why do you change it so often?

Always change at 30k. Just like to keep it fresh. And I tow a travel trailer a lot.


.

 

[zonzin]

isnt the transfer case suppose to use "toyota 75w" as there are a ton of additives in this fluid compared to other fluid people are using

The RP is a direct replacement and with the Yota lube running 50$+ a qt....



.

 

[dedonderosa]

yeah i have read that a lot of axle/diff manufactures recommended reg dino gear oil, as it will actually dissipate the heat out of the ring and pinon better and will cling more to them rather then slide off as synthetic gear oil would do. the synthetic gear oil will stay cooler but the gears themself will actually be hotter and usning dino gear oil the oil will be hotter and the gears will be cooler as its sucking the heat out of the gears.

there was an article stating this from a large diff/axle manufacturer but i cant find it .

dont quote me on this im just telling you what i came across thats all.

 

[dedonderosa]

i think im overthinking all this lol