2018 4R - 5000mi Rear Diff oil - full of metal particles

Why not fill the diff with cheap motor oil, drive slowly around the block and then dump it. Do that a couple times and the diff would be well flushed. Then put diff oil in.
 
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.

Been using the SynPower Valvoline.
 
Yikes, I've never heard this one. Perhaps it's a good idea when rebuilding a dif so the brake cleaner can completely flash off, but in a sealed dif? My (probably unfounded) concern would be that any residual brake cleaner would do something to degrade the fresh oil. Won't be using this practice myself - simply swapping gear oil has been fine for my vehicles in the past, and isn't a guideline I've ever read during the process of rebuilding my M3's dif.

For rear and front diffs, I left both plugs removed and pumped a bit of new oil to drain the leftover metal particles. I overdid it a bit, but I can tell you, after you drain your oil, very little extra debris come out. So I would say, don't worry about flushing, just do periodic maintenance.
 
Yikes, I've never heard this one. Perhaps it's a good idea when rebuilding a dif so the brake cleaner can completely flash off, but in a sealed dif? My (probably unfounded) concern would be that any residual brake cleaner would do something to degrade the fresh oil. Won't be using this practice myself - simply swapping gear oil has been fine for my vehicles in the past, and isn't a guideline I've ever read during the process of rebuilding my M3's dif.

Diff is not sealed, it's vented. Brake cleaner also evaporates quickly. Spray in, let it drain out, give it 5 minutes, done. I've cleaned every single diff I've ever serviced without a single issue.
 
Normal. When metal gears break in, the metal from break in has to go somewhere. Stop worrying and follow the maintenance schedule.


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Brake cleaner doesn't last long. Do wear eye protection.

Exactly my point. flushing the diff out will not harm a thing. Even if there was a small pool of it somewhere, it'll evaporate in minutes if not faster. Buch easier to clean a diff out that has an actual diff cover so you can see what you're doing but either way shooting a can through the fill plug and letting it all drain out the drain plug is better than nothing.
 
I have been doing exactly that for 35 years on my 8'' axles.......use the little red flex hose on the brake cleaner and point it all around. I blast into the top fill hole with my air hose and it evaporates the cleaner, and when it stops coming out the bottom I cap the drain and fill it up to the top hole...all good.
 
Why the difference in Gear Oil???

Sorry to resurrect an old thread, but my searching has not found any clear answers.

Toyota Differentials (OEM) run LT 75W-85 GL-5 Gear Oil

Nitro Gears recommends using 80W-140 Gear Oil.​

So, I am curious...
:noidea:

Why the difference?
What is the risk of running the lighter oil with the Nitro Gears?


Background information: I have 165,000 miles on my original 3.73 gears with heavy loads and tons of towing. I had zero metal flakes on the drain at 75,000 miles and 150,000 miles. Last month, I upgraded to a Nitro Gears 4.56 gear set. I did the initial break in then drained and refilled with 80W-140 with the expected fine metal shavings a decent looking oil. I refilled it with Castrol 80W-140 per my mechanic's advice. Since then have put 2,500 miles on the vehicle, and I'm about to change the oil again just to ensure everything is okay. I have noticed that my fuel economy is way down. Power is up, but but I can't break 13MPG unloaded cruising at 55 MPH (I was as high as 18MPG fully loaded - not towing).
 
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I changed the OEM factory diff fluid on my 2005 at 100,000 miles, and don't recall any issues - including pieces in the oil. It was black. Viscosity seemed thin. Hard to judge.

I used Valvoline 80/90 weight - which is recommended (with normal use)

4runner has always driven noiseless and fine.

I'm at 150,000 miles and may do a 6 quart DF soon. Rear-end holds total 12 quarts.

D/F is all Ill do. Hope 6 quarts Drain out - or I'll have to do it twice or call a dealer for advice.

I never changed this on any car I ever owned. Had a new GMC Jimmy - sold at 88,000 miles at ten years old.
two-year-old Cadillac - never touched it - 100,000 miles.

What is the manufacturers recommended maintenance schedule?

I think the posts here are way over maintenance on any rear ends (that don't tow).

The normal service interval for the differential is 90,000 miles so if you cut that in half you should have no issues. The severe service interval is 60,000. differential service - Bing
 
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I changed the OEM factory diff fluid on my 2005 at 100,000 miles, and don't recall any issues - including pieces in the oil. It was black. Viscosity seemed thin. Hard to judge.

I used Valvoline 80/90 weight - which is recommended (with normal use)

4runner has always driven noiseless and fine.

I'm at 150,000 miles and may do a 6 quart DF soon. Rear-end holds total 12 quarts.

D/F is all Ill do. Hope 6 quarts Drain out - or I'll have to do it twice or call a dealer for advice.

I never changed this on any car I ever owned. Had a new GMC Jimmy - sold at 88,000 miles at ten years old.
two-year-old Cadillac - never touched it - 100,000 miles.

What is the manufacturers recommended maintenance schedule?

I think the posts here are way over maintenance on any rear ends (that don't tow).

The normal service interval for the differential is 90,000 miles so if you cut that in half you should have no issues. The severe service interval is 60,000. differential service - Bing

It's not so much the interval or the maintenance... I'm not having any problems with the new 4.56 gears at all. No noises, no problems on first drain/fill - I'm just having a problem with my fuel economy dropping so low since changing gears. That's why I'm trying to determine what I am going to fill up with at this next change. So far, most people I have talked to have not gone up to a 80W-140 after regearing.
 
Sorry to resurrect an old thread, but my searching has not found any clear answers.



So, I am curious...
:noidea:

Why the difference?
What is the risk of running the lighter oil with the Nitro Gears?

.
A heavier weight oil is better for the longevity of the gears, and they don't really care about your MPGs.

I've been running 140w for close to 200k miles on my Nitro gears, but I wouldn't think twice about switching back to a 90w.
 
A heavier weight oil is better for the longevity of the gears, and they don't really care about your MPGs.

I've been running 140w for close to 200k miles on my Nitro gears, but I wouldn't think twice about switching back to a 90w.

Yeah, since the initial post I have talked to a few guys about this, and 2 out of 5 people are running the 90W with no problems. However, like most people with 4Runners, they don't really care about their fuel economy. So, they don't track it. Although they have noticed the dash numbers are usually higher since regearing. Most of them have 285+ tires. I am running 255/75 C-Loads because I drive my vehicle so much, and I hate throwing away money in fuel.

Thanks for the reply!
 
Yeah, since the initial post I have talked to a few guys about this, and 2 out of 5 people are running the 90W with no problems. However, like most people with 4Runners, they don't really care about their fuel economy. So, they don't track it. Although they have noticed the dash numbers are usually higher since regearing. Most of them have 285+ tires. I am running 255/75 C-Loads because I drive my vehicle so much, and I h ate throwing away money in fuel.

Thanks for the reply!

When you cruise on highway now how do your rpm at 60 mph compare to previous with 3.73 gears? 3.73 to 4.56 is a significant change.
 
I had 1 mile on my TR4 OD when i drove it off the lot; dumped factory rear diff oil at 2200 miles and it looked dark gray and had a good amount of metal shavings. For me its cheep insurance!
 
I drained my rear diff from new every 10K

1) first drain at 10k was very dirty. Thick and grey

2) second drain at 20k was also grey and thick

3) third drain and 30k came out clear, not much grey at all

I plan to service the rear every 30k from now on.


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