[skag1T]

Just did a 5000 mi oil change and rear diff oil change to my 2018 4R SR5.
Thank you for the DIYs on this forum, awesome community.

Diff drain was FULL of metal particles. Never seen anything like it. It reminded me of the 2001 A Space Odyssey movie: "My God, It's Full of Stars"

I am not worried, just wanted to share: - maybe it's a good idea to change rear diff really early.

What are your thoughts...

Will look at the rear diff again in 10k miles or so. The car is new, so far I am doing mostly city/hwy driving with a light mix of easy forest roads now and then.

I also took samples and will do a Blackstone analysis.

Still trying to figure out how to post decent size pics ...

Circled in red is a 2mm metal piece !!

The silvery color from the oil drain pic is from fine sand-like metal particles in the oil !

[2016 4Runner SR5]

Pretty common with new gears. Even after a regear you're supposed to go through 3-4 heat cycles and change the oil. I have to assume these rears are built, filled, and shipped off without any kind of break in or anything like that. I plan to service my diffs this coming week since i'm at about 11.5K and haven't touched them. I will run it in 4wd for a short distance to stir up the front diff and then service both just for the hell of it. I expect to find it pretty nasty in there but hope it'll be clean when I perform the next service. What oil did you use in the diff?

BTW, engine oil every 5K is also a good idea IMO I'm not a fan of the 10K the book says

[TexasTEQFan]

Run it, the paste isn’t a big deal and it looks like you had one small shard of metal so you can drop the oil again after another 10K and see what it looks like. You’re under warranty if something really happens.

Unrelated but this is what I found in my FJ40 a few years back after a couple hundred thousand miles. After opening it up to have a look I was missing a cone thrust washer under one of the spider gears and I think these were the pieces of it. My center pin was chewed up as well from the spider gear slop. Sourced a new center pin, and grabbed a spider gear and thrust washer from a friend installing an ARB and drove it 5 more years, finally replaced the whole third member this spring after a clutch job simply because of the play after all the miles. I say this because I had a scarier find (although not in my T4R) but in my experience Toyota makes pretty darn tough drivetrain components.

[2016 4Runner SR5]

Always a good idea to flush it out with a can of brake cleaner also. Just spray through the fill plug and let it run out the drain plug. Move the can around to get as much of the crap out as possible. You'd be surprised how dirty the stuff is that it washes out of there. Much easier on diffs that have normal diff covers but works well for us also.

[skag1T]

Originally Posted by 2016 4Runner SR5

Always a good idea to flush it out with a can of brake cleaner also. Just spray through the fill plug and let it run out the drain plug. Move the can around to get as much of the crap out as possible. You'd be surprised how dirty the stuff is that it washes out of there. Much easier on diffs that have normal diff covers but works well for us also.

Excellent idea, will do that next time.

Do you spray in the whole can ? Or just enough to see clean liquid coming out ?

[2016 4Runner SR5]

I came over from American cars and trucks so on Dana axles with normal diff covers you just wash until it's clean. Since we can't open the diff and see what we're doing, I just use the plastic straw that comes with the can and shoot the whole can in there. I move the straw around as much as possible to try and clean as best as I can. Now hold on to that plastic straw with 2 finger tips because if it pops off the nozzle on the can which does happen it'll likely end up in your diff and you won't be able to get it out.

[83Mule]

I did mine at 25K and I have to say there were no shards and maybe a 2mm layer of ''fur'' on the mag......your's looks bad IMO for the miles. My oil still had a little green tint in it too.

[skag1T]

Originally Posted by 2016 4Runner SR5

I came over from American cars and trucks so on Dana axles with normal diff covers you just wash until it's clean. Since we can't open the diff and see what we're doing, I just use the plastic straw that comes with the can and shoot the whole can in there. I move the straw around as much as possible to try and clean as best as I can. Now hold on to that plastic straw with 2 finger tips because if it pops off the nozzle on the can which does happen it'll likely end up in your diff and you won't be able to get it out.

I've seen one of those diffs with the cover off.

Your advice is noted, will do the brake cleaner flush next time.

Much appreciated.

[skag1T]

Here's the Blackstone analysis of the Rear diff Toyota Factory fill after 5000 miles. (attached)

Basically they are saying the high amount of metal in the oil is no surprise from a break-in sample.

Iron came out at 177, Boron at 207 and Phosphorus at 1411 (!). The rest of metals are 0 or under 5.

cSt viscosity @ 100 C (212 F, which is working temperature) came out as 11.07, which seems to be typical for a 75w-85 gear oil.

I expected a lot more spread on the metal traces. Instead there are 2 small spikes for Iron and Boron, and a huge spike for Phosphorus.


Here's a comparison of the cSt-s @ 100 C for various gear oils:

AMSOIL Severe Gear 75W-90 cSt @ 100 C = 15.9 (this is what I used)
Mobil 1 75W-90 cSt @ 100 C = 14.6
Red Line 75W-90 cSt @ 100 C = 16.1
Red Line 75W-85 (a.k.a., LightWeight Gear oil) cSt @ 100 C = 11.5
MOTUL Gear 300 75W-90 cSt @ 100 C = 14.2
SynPower Valvolilne High Performance 75W-90 cSt @ 100 C = 15.6

Looks like Red Line 75W-85 would be a perfect match as far as working temp viscosity.

[2016 4Runner SR5]

What was the overall condition of the oil they tested? Any concerns with the metals found in the oil?

[TEN613RPro]

Originally Posted by 2016 4Runner SR5

What was the overall condition of the oil they tested? Any concerns with the metals found in the oil?

It's in the attachment. Short- They are not concerned for this during a break in period.

[coltm4]

I did mine fairly early too, looked every bit as bad as yours and maybe worse. I changed again 5000 miles later with Mobil Delvac 1 gear oil. The second change definitely looked better with MUCH less on the magnet. Both front and rear had a ton of black paste on the magnet. The transfer case oil looked like it was new. Frankly, I don't think it is worth the time or money for the oil to be drained out of the transfer case unless you submerged it in water for a while.

[Jeremy556]

Perfectly normal for a R&P break in. My Nitro gears had considerably more debris after a 500 mile break in. They have been going strong for about 150k miles since then.

[Kenstaroni]

I did mine about the same time and although not as bad as yours, there was some metal on the plug. I helped a buddy change his (2017 pro) which hadn't been done at all yet, at 40k miles and it was cleaner than mine was at 5k...go figure...lol

[skag1T]

10,000 miles update

So I did a complete Driveline service and an oil change.

Front diff - dirty, lots of metal particles (see pics). This is Toyota Factory Fill after 10,000 miles.
Transfer case - clean, looked like new oil.
Rear diff - dirty, lots of metal particles, about the same as it was at 5000miles (see previous posts).

I bit the bullet and got the Toyota 75W "special" transfer case oil ($67.- at the dealer). The TC only took 1 can (1 liter) before it started to drip out of the fill hole, just like the manual says [ 1.1 qt (1 liter)].

The 2 diffs got AMSOIL Severe Gear 75w-90.

Besides regular daily commute and road driving, I am doing light offroading in the weekends, forest roads mainly, nothing extreme, no rock crawling or deep water crossings. I am still surprised at the amount of metal drained out of the differentials.

So if people go 50k - 100k miles before servicing the diffs, this metal "sand" stays in the oil all this time and the diffs are still working ? To me, oil with metal particles in it does not lubricate that well ....