Rear Diff maintenance?

About to do my 40k oil change and also want to replace my rear differential fluid as well. I tow a 7k camper 5-7 times a year, anywhere from 1-5 hours each way. Am I crazy for wanting to replace the rear diff fluid? I was looking at Valvoline

$39 75W-90 GL-5 Limited Slip, Ultra Long Drain 500k Miles, Manual Transmission, Gear/Differential Lubricant (1 Gallon)

75W-90 gear oil from autozone for $10.99 a quart. Also, anyone have a part number for the rear diff fill and drain plug gaskets? I've reused aluminum gaskets with much success, and if they are aluminum I'm assuming I'd have the same success!?

 

Diff fluid changes are normal maintenance. As is trans and xfer case drain and fills.

 

I changed my diff fluid for the first time at 20k. It was really bad. I don't tow but I offroad and load the truck to max payload often enough. You should change it now. I will check it again to see the condition after 10 or 15k to see how it wears normally.

 

You can get the gasket kit on Amazon for 10 bucks. I recently bought 24 quarts because the price was amazing at 8 bucks a quart for synthetic. Normally it's twice that at autozone.

 

I do front, rear and transfer case every 30k.

Differential and Transmission Drain Plug Crush Washers Gaskets Fits for Toyota 4runner Tacoma Tundra FJ cruiser Land Cruiser, Replacement for the part# 12157-10010 90430-24003 90430-18008

$7 Differential and Transmission Drain Plug Crush Washers Gaskets Compatible with 4Runner T acoma T undra FJ Cruiser Land Cruiser, Replacement for The Part# 12157-10010 90430-24003 90430-18008

https://www.amazon.com/dp/B07DFJ24WD

I use Amsoil in the cases, but I’m sure Mobil 1 or something similar is just fine.

 

Rear diff fluid (non-synthetic) will always look “bad” and smell really bad when you change it. It’s gross stuff. The synthetic fluid is more pleasant appearing and smelling when changing in my experience. None of that means it’s not working though. If you have water in it, that’s bad. If it’s murky and appears contaminated, that’s bad. It gets hot and experiences a lot of shear and should be changed at the recommended intervals or sooner for severe use or deep water driving.

 

I never buy fluids at Auto Zone or any other auto parts store. Cheaper at WalMart if they have what you need. 3 diff oil changes on Tacomas and 2 on Tundra and have never changed a washer and never had a leak.

 

Changing all your fluids at 40k is certainly a good idea. The washer kit that was posted above is certainly a good idea, I think I actually bought the same one.

For oil I used this: https://www.blauparts.com/toyota-tundra-transfer-case-differential-fluid-change-kit.html It is the correct oil for both front and rear diffs, and more importantly your transfer case. That 75W oil, from Toyota, is extremely expensive. Of course if you don't have a 4x4 you can save some money and not buy the full kit.

 

It is not about saving pennies. Just don't need to change them and never have.

 

Ravenol claims the 75W is a direct replacement for the Toyota transfer case fluid, but the additive packs are not the same between the two. Don’t know how much it matters, but they are not the same fluid.

 

Changed my rear diff, front diff and transfer case with the Valvoline. All is well.

Valvoline Flexfill SAE 75W-90 Full Synthetic Gear Oil 1 QT, Case of 4

$63 Valvoline Flexfill SAE 75W-90 Full Synthetic Gear Oil 1 QT, Case of 4

https://www.amazon.com/dp/B08K9CGB6Y

 

I changed front, rear differential and transfer case every 30,000 with synthetic 75-90. None of the old fluid looked bad at all. Just try to keep up with it and you will be good.

 

Yes I have seen that too. I tried to do my best homework on it, and so far I've used 4wd quite a bit and have had no issues. I do plan to change it once I hit 30k miles.

Having said that, another forum member had almost 60k on his Ravenol 75w transfer case fluid and when he drained it, it was very dark. However, the oil analysis showed it was in perfectly fine shape. So even though the additive packages might be different, it still may be suitable?? Who knows lol. Let's just hope it holds up and keeps working.

 

Changed the Tcase oil on my Tacoma at 50k and it looked like it came out of the bottle. Not sure if 4wd use has any effect on the oil but I figure less then 1% of miles are with 4wd engaged.

 

Yeah I honestly don't know if it has an effect, but I sort of assume it does?? I know when I drained the fluids that were in my T-case and diffs, the front diff and T-case looked pretty damn decent. I assume it was OEM Toyota fluid, but as I bought the truck used I don't have the full history on it. I do know it was a highway queen though so it probably never got used in 4wd lol.

If the Ravenol is shit when I change it 20+k miles from now, I'll spend the extra money on OEM stuff. I'm just a cheap bastard.....

 

Yep I do my front/rear and transaxle diffs every 3-years. I buy the kits from Blauparts.com and they have the Ravenol brand and the bottles have cool nipples that extend out so you can hold them up to the fill holes and just squeeze it in...no stupid pumping required. These are my notes from my last job:

-Front Diff: Do FIRST as there's not a lot of room so have to use multiple bottles. Takes 2 Qts of 75W-85
-Transaxle: Takes 2 Qts, 75W (do last as it's next to the hot exhaust pipes)
-Rear: Takes 4 Qts, 75W-85

Dang, when I ordered the kit in July 2021, it was $135. Now, it's up to $196...crazy inflation we have: https://www.blauparts.com/toyota-tundra-transfer-case-differential-fluid-change-kit.html

This is a great video of a guy using the Ravenol oil....very helpful...

 

Doesn't hurt to do more than less! I've asked a number of mechanics on their interval opinions and they say every 3-4 years, 40,000-50,000 should be fine. My Tundra is primarily used for pulling our RV in the summer, 5-6 times, and when we get bad winter weather so I'm only putting 5,000 miles a year. She only has 46,000 miles on her.

 

Yeah I'm in a similar boat. I might put 5k miles on a year. I just use it when I need to for towing, moving big stuff etc. Or when my DD or the wifes need some work. I'm sure it'll be a while until I drain the Ravenol that's in my truck lol

 

I just did mine for the first time this spring. It was actually the first time I have ever changed my diff oil on any of my trucks. My truck had about 90,000 miles on it and the oil still looked good.

 

I do my diffs And transfer case every 60k just did my first one and fluid looked fine. Do the trans at 100k

 

Not sure what kind of driving people are doing but i do some offroading a couple times a month and do not tow, and my fluid looked as black as the devils heart when i changed it at 20k. Maybe it was because it was the first change, but I cant imagine waiting longer than 20k for the next change.

 

I barely towed and changed my front and rear and transfer case every couple years on my Gen2.

 

Royal Purple Syncromax is what I use in the transfer case. It is compatible and a direct replacement for the Toyota gold fluid per Royal Purple specifications

 

So is the Ravenol, but both might not exactly the same. Still probably both good enough though. Time will tell. I personally stay away from RP products, but that's just me based on some experience from some racing friends.

 

Yeah I have never used any of their other products except for this one. Have not had an issue with the Synchromax over two vehicles now. An no clue about any of their other stuff

 

I changed diff oil at 100k in my Fords if I kept them that long. No drain plugs so the only way to change was to pull the cover. I think Toyota is the only truck manufacturer that recommends changing at 30k. I dropped the pan and changed trans fluid every 30k on Fords.

 

I see you found my analysis. Fluid was still good. I have much better fluid in there now, HPL 75w, Dave made me a batch and didn't upcharge for it.

I'm gonna be running my diffs at 100k intervals from now on, I will be draining my current fluid after 10k though since I just regeared to 5.29s.

99% of people never change their diff fluid, and they do just fine, how many rear diff failures frem lubrication failures have you heard of? Any fluid change at any interval you want to do will be beneficial and prolong the life of the axle assembly. I had 59k miles on my last UOA, lots of offroad and towing, temps from -18F to 110F, and it came back great. Which is why I'll be doing 100k intervals with an even better fluid.

If I didn't keep my vehicles forever, I'd run the cheapest fluid I could buy that meets spec. I buy great fluid thats above and beyond labeled specs, get an analysis on it, and go from there.

Everyone is different and runs the brand of oil they prefer at the intervals they feel comfortable to with.

 

Haha yes I did. I can see that some of the values are less than that of Toyota, but it was nice to see it at least held up with nearly 60k miles on it.

And you are 100% right, most people never even change their fluids and failures are rare. I think the biggest concern here is the transfer case, not the diffs. Now if the Ravenol doesn't hold up or causes me some trouble using 4wd, I'll switch back to OEM fluid for that.

I think the other big issue, at least for the T-case, is lack of options for straight 75W fluid. Front and rear diffs are easy, and I probably would have ran something else other than Ravenol if it hadn't been for that big combo package from Blauparts.

 

This is what the local dealership sold me today for $10.59 a bottle. I'll be changing out the front and rear diff fluid this weekend. If the front diff oil looks clean I don't think I'm going to change the transfer case oil any time soon.

 

Two thoughts:

1 - if you're driving in deep water, get a breather kit. otherwise your diff will suck water. (the diff gets hot with use; when it hits cold water, it suddenly sucks in air ... or water if there's no air) I think it was $25 maybe? I put one on mine. When it rains here, it *really* rains.

2 - complaining about Toyota tcase fluid price is a bit odd? I researched this when I bought my '15 used with 96k miles on it. I determined better to be safe than sorry. $100 more or something is nothing? That said I didn't understand why it came in a tin can that I had to puncture with an old fashioned can opener!!