Maintenance timeline - front & rear diffs and transfer case

OK, I am going to assume that I am missing it somewhere but up to 120k miles, routine maintenance never says more than "inspect" front or rear diff fluids*

*except under special operating conditions, which has a footnote saying when PRIMARILY driving under those conditions. then it lists them being changed every 15k when primarily towing, using a rooftop box or heavily loaded.

FWIW, dealer quoted $442 for both differentials and transfer case. Dealer recommends this at 30k miles but its easy money for the dealer to recommend it...

So, how often does it really need to be done? Are Toyotas really that fragile?

My F150 manual called for differential fluid at 150k so a dealer recommending it at 30k seems a little soon.

 

Usually 60K miles for diff fluids and trans fluid is the general rule of thumb. Some owners do it more often because they're a little paranoid. The dealer just wants money.

 

Some vehicles never have the differentials touched and work fine. (like dad's RAV4 but don't follow our example there!)

The big one is if water gets in, it should be changed no matter the mileage.

But otherwise these are big, dummy simple, durable gears spinning in there. But gear oil is relatively cheap, diffs aren't, and the procedure is straightforward.

I'd change it as insurance (if DIY) and see what it looks like coming out as well as the magnet on the drain plug if you want to be involved.

Personally, I lean towards getting the factory fill out sooner after break in (~25k miles for me, when I purchased it) and then I'm probably going to ignore it a while (until maybe 60k-80k) unless I get into water crossings.

You have a pretty wide margin for error here.

 

Car Care Nut recommends diffs and transfer case every 30k. For me that’s once about every two years. Can’t hurt. I did mine in well under one hour, and saved $$.
https://www.google.com/search?q=car...ial&ie=UTF-8&oe=UTF-8&hl=en-us&client=safari#

 

If I had a place to do it myself, I probably would just do it, see how it looks and go from there in the future. 30k for me is 18 months.

 

Think the front diff needs to be on same service interval as rear? My front diff always looks so clean when I drain it with rear diff.

 

I did the trans, diffs, and transfer case at 75k.

Seemed like a reasonable number to me.

They were all pretty easy to do yourself.

 

I did my front, rear, and transfer case at 30K miles. The transfer case fluid looked new, the front differential was just starting to change color, and the rear differential fluid was dark. Now I didn't get a lab analysis done, but I adjusted my change interval to the following: front and rear differential every 15K and the transfer case every 30K. At 15K miles the front differential fluid looked new, and the rear diff fluid had just started changing from clear to dark.

 

60k for me.

 

Don't forget about brake fluid, coolant and power steering fluid changes [if you want vehicle to last]. Fluids are cheaper than parts.
Brake fluid absorbs moisture [h2o], coolant becomes acidic and eats gaskets. Listen to the naysayers and do nothing or take care of your investment if you want it to last.

 

The rear diff gets very dark and nasty after 25k. The front and transfer can go much longer.

 

Back when I used to work for Jeep, it was recommended that diffs, transfer and trans was changed every 30k.

 

and care care nut has recommendations for those as well

 

Did mine at 60k, dealer never reminded me to do earlier. If i did heavy off roading maybe every 30k. Approaching 100k, so time to do plugs and everything soon.

 

translation necessary for this 85 year old‍♂️‍♂️‍♂️‍♂️

 

Jesus christ thats a lit of money. You can do all 3 for under $100. Hell come over and I do it for a case of beer.

 

I change them often for TW and 4runner members. Definitely recommend every 30k with some of them I've seen that went too long.

It takes 20-30 minutes tops per diff/ t-case. It's very simple with a few tools. New crush washers and torque the drain plugs to spec.

 

Love to hear from the mechanically sound folks, why such a big gap between F150 and 4runner? Is Toyota parts fragile? Does Toyota have a better reputation in reliability because of short service intervals and vehicles like F150 is better built (Ford tough) than 4runner?

 

Not an expert but complicating factors likely include…

- Lower maintenance cost on paper (ex. The 1.0 EcoBoost wet oil pump belt being specced at 150(?)k but sometimes failing before that, but after warranty expires.)

- How much oil fits in there, how it’s built compared to its expected use case

- Is that 150k “normal” service or “severe”?

The 4Runner’s “normal” service recommendation might be indefinite with periodic inspections.

My Kia’s transmission fluid was specced at “never” for normal, 60k miles for “severe” (which was a list of actually quite normal conditions)

 

Did the 4Runner rear diff at 15k, was dark and dirty. T-case and front diff at 30k, still clean.

I do the rear more often then necessary as the truck tows a lot.

Did my Tacoma rear diff at 10k going off the experience with 4Runner rear end and it was still gold in color and clean.

 

Out of the dozens of Toyotas I've done, no matter the mileage, almost always the T case is still a nice color. Diffs get darker much faster.

 

did all three around 40k but the truck has a new front diff at like 30k.

 

You can probably never change the diff fluid and it will be fine. It’s thick heavy oil that’s just keeping the gears lubed. It just gets discolored over time. Like others have said if there is water in there then definitely change it. Also check the level and top it off periodically. Changing it at anything less than 100K seems like wasting time and money to me.

 

What do you use for xfer case fluid?

 

The 150k was for normal. I traded it at ~160k and never had it done (I would have done it myself on schedule but between 140 and 150k I lost my house in a divorce and wasnt in a great frame of mind to take care of things that seemed inconsequential at the time. By the time it was over 150k, I knew I was trading it before long to sever that link to my past life. It was a great truck and in some ways, I do miss it). It wasnt like people were having issues with differentials though (and Ford sells a LOT of F150s).

The 6-speed transmission I had in the F150 is the same ZF that BMW uses (so i am told by BMW people). Ford recommends changing transmission fluid at 100k, ZF recommends 60k, I had it done at 80k (and if I had kept it, would have had it done at 160k).

 

I think for most mild driving conditions these are fine. Don't need to do heavy off roading or heavy towing to need them sooner. Lots of stop and go traffic, high heat use, etc I would do them sooner.

 

This guy lol

 

Gear oil is not extremely thick. 75W-90 gear oil is about as thick as 10W-30 motor oil. But gear oil has different chemistry and is deliberately given a different numerical designation so you don’t mistakenly use it in your engine.

I stopped using Amsoil Severe Gear 75W-90 after I noticed how dark and full of metal debris and sludge the rear diff oil was after 15,000 miles. Now using Valvoline 75W-90 and it’s much cleaner.
Using the same for transfer case and front diff but at 30,000 mile interval.

 

I like to use ECGS as gear oil experts. I have regeared but don't choose the dino 85w140. Synthetic is my choice.

https://eastcoastgearsupply.com/ft-2536-ecgs-gear-oil-recommendation.html


Opinions on specific gear oils:

Royal Purple: In our opinion one of the worst gear oils made
Valvoline synthetic: Better than royal purple but dino out performs
Ford synthetic: Probably Valvoline not the worst but think dino is better
GM synthetic: Similar to ford
Toyota synthetic: Average same performance as most dino's I think lucas is better
Mobil 1 synthetic: Better than economy dino's and is likely comparable to Lucas or other quality dinos with additive packages
Amsoil severe duty: Better than all economy Dino's and all synthetics on the market, but marginal over a quality dino with additive package
Redline shockproof: Same as amsoil

The only synthetic's I would consider are Amsoil, and redline, along with some industrial synthetic's that aren't really marketed to your everyday user. But would only consider if I was trying to control a heat problem, or shock load issue generally related to doing something the differential was never designed to do in the first place.

In the end changing the oil more frequently will result in less wear and longer life in and will cost less money.