Please give me a reason why I need to change the rear diff oil every 25K miles

4SKIN

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Unless Toyota makes there ring gear and pinion out of aluminum I just don't see that routine maintenance as necessary. Gear oil doesn't break down. The only thing it could do is get contaminated with metal shavings. But that would be a sign of something else wrong. Enlighten me.
 
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Toyota recommends changing differential fluids based on level and color but more frequently if carrying heavy loads or towing and off roading. Water crossings, off road, Sandy dusty environment might need more frequent changes specially the transfer case. Send the oil for a lab analysis and follow their recomendation.
 
Unless Toyota makes there ring gear and pinion out of aluminum I just don't see that routine maintenance as necessary. Gear oil doesn't break down. The only thing it could do is get contaminated with metal shavings. But that would be a sign of something else wrong. Enlighten me.

"I just don't see that routine maintenance as necessary"

I see the point of routine maintenance. Things wear out, nothing lasts forever. If you use anything it will show wear, if you don't maintain it, it will no longer function. it's a simple truth to the physical reality where we all live.

"Gear oil doesn't break down"

gear oil does break down, it get's contaminated and oxidizes. It's viscosity will increase and so will friction between the contact surfaces.

very small metal shavings in the form of a paste is normal. Large curls of metal means something is wrong.

Once you skip out on routine maintenance your bearing races will have scratches and pitting, this will cause more and more wear. This wear will accelerate as the damage continues to get worse and worse. you can go 500K miles with these gear sets if you perform regular maintenance.
 
If you use a high quality synth gear lube, don't do water crossings, and your seals are intact then you should be able to go a longer interval. I wouldn't hesitate to do 50k on a fill of Redline.
 
I can't, 25k seems a little short for gear oil. Unless you submerged the axle at some point and didn't have an extended breather, then I would check it pretty quickly.
I would do 50k at the very least - if it just sees typical highway/city driving I probably wouldn't mind pushing that a little further. There's no such thing as a "forever" or "everlasting" oil, gear oil does in fact break down, just much more slowly than motor oil. If it didn't then all the companies would sell you used oil at a full mark-up and nobody would bother with the headache that is recycling.
 
It's all personal, based on individual experiences. I've had rear diff oil changes at 30k miles that were like pudding coming out on some vehicles, and looked like new oil on others. The nasty vehicles I cut in half (or so, just less till it was acceptable to my eyes), but I always change all fluids at Least once every 3 years, which translates to somewhere in the low 30k mile range for me... except the '66 bug, that's more like 10~12k in 3 years.

Why? Because an ounce of prevention is worth a pound of cure. A hundred bucks in fluids and a couple hours time beats the snot out of the cost of replacement parts AND the time spent fixing, nevermind the downtime and inconvenience of failures at times when the vehicle is needed.

I also change tires Before they hit the TWI's, brake pads Before they start squealing, and toss my fancy battery charger (does repair too) on good batteries a couple times a year. Part of it is the joy of wrenching, part is so my wife can 100% rely on any vehicle at any time without being stranded, part is because I know that maintained vehicles simply operate better and last longer and I want to protect my dollars spent.

But, as I said, it's all personal. My brother-in-law has been letting his wife drive his kids around in a car with bad wheel bearings for 6 months now. You can hear that dang thing Howling from a mile away, just doesn't care... he'll fix it when it fully breaks, something learned from his dad.
 
OK you've convinced me, I'll change it, but those fill and drain plugs scare the bejesus outta me. The only 24MM socket I have is a 12 point and I didn't like the feel of it. I tried a 15/16 6 point and that seems to fit better, but I didn't like the feel of that one either. I'll hunt down a 24 6 point and see how that fits. I need to pick up the crush washers from Toyota anyway. I've learned that sometimes it's best to let sleeping dogs lie and I thought this may be one of those cases. We will find out.
 
OK you've convinced me, I'll change it, but those fill and drain plugs scare the bejesus outta me. The only 24MM socket I have is a 12 point and I didn't like the feel of it. I tried a 15/16 6 point and that seems to fit better, but I didn't like the feel of that one either. I'll hunt down a 24 6 point and see how that fits. I need to pick up the crush washers from Toyota anyway. I've learned that sometimes it's best to let sleeping dogs lie and I thought this may be one of those cases. We will find out.

Hopefully no one needs to say "make sure you can remove the fill plug before you drain the oil", but there it is.
 
Why change it? Because oil and maintenance is cheap. Certainly cheaper than the alternative.

They even give you a drain plug……sheesh.
 
Why change it? Because oil and maintenance is cheap. Certainly cheaper than the alternative.

They even give you a drain plug……sheesh.

this is probably the best point made in the thread by far. nothing else needs to be said.

land rover did one better than that...

on the 2006-2012 L322 they use the ZF transmission without drain and fill.

They claimed it was a lifetime service free transmission. ZF then promptly release a statement saying they recommended service on heavy use and towing @ 60K miles and normal use @ 80K. Also released a retrofit drain and fill kit so you could service your ZF transmission.

I can hear the marketing director making up the lies and then putting it into the sales brochure. why ask the transmission manufacture? The marketing guys know everything.
 
The rear differential have an air breather and moisture and other small particles can get in there and break down the gear oil. For me it's another PM I like doing, gear oil is cheap and the differential has a drain/fill plug that are easy to access.
 
Gear oil DOES break down.

Toyota put that service interval for a reason. They aren't making money by making it 25k instead of 50k.

Heat is big in a differential, and is what makes gear oil break down and leads to bearing failure. A fluid change is a lot cheaper than a diff rebuild, even if you do it yourself.

Take it somewhere if the drain plug scares you...
 
And like others have said already, oil does break down. All of it. Even as it sits it begins acidifying once it’s in the wild.

The thought lifetime oil, or lifetime anything really is about the stupidest thing ever. Some marketing jackass thought they could sell even more laziness to people. Drives me damn nuts how many new cars don’t even have a way to check oils easily. Makes me want to throw things.

Sucks that everything has to be so dumbed down in automotive now…. Crap like transfer cases not engaging 4x4 on my 17’ tundra because a wheel sensor goes down, “muh yaw on slippery conditons, please government save me with some stupid FMVSS rule cause I can’t drive, I has no smarts”…..……I guess everything is dumbed down really. All it does is provide reinforcement to the idiocy. I also like the “welp” time for a new car every 5 minutes. “Ain’t worth it, time for a new one, wore out…..blah blah blah” from all of lazy people who’d rather pay copious sums of money via that “great deal” on a new car financed on the never never plan. 60k for the next one was fine…..but a few dollars in repair was too much to ask.

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Sorry for the rant. I feel better now.

In all seriousness though, just change the dang thing. Go buy an oil drain container for like 15 bucks at any parts place. The tools to even do it literally cost nothing. It’s still less than a tank a gas. Go get a 6
Point socket if need be.
 
I’ve had vehicles much less reputable for reliability (Jeep, Dodge) reach 300k miles without a diff fluid change. If you’re not towing or off-roading, the diff and factory fill will easily reach most manufacturers’ definitions of “lifetime”, and then some.


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this is probably the best point made in the thread by far. nothing else needs to be said.

land rover did one better than that...

on the 2006-2012 L322 they use the ZF transmission without drain and fill.

They claimed it was a lifetime service free transmission. ZF then promptly release a statement saying they recommended service on heavy use and towing @ 60K miles and normal use @ 80K. Also released a retrofit drain and fill kit so you could service your ZF transmission.

I can hear the marketing director making up the lies and then putting it into the sales brochure. why ask the transmission manufacture? The marketing guys know everything.


I have a L322, 2012 with 167k miles. I am convinced the ONLY reason the transmission has NOT burnt up in that thing is because the previous owner had some warranty work done for a output shaft seal, during which the transmission fluid was replaced at 70k-something miles.


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It’s got a drain plug and a fill plug on both front and rear diff’s. It’s easy compared to some. Even the trans pan has a drain plug.

Easy piesy compared to some.


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Fluid changes are a scam invented by big oil to take your money, I don’t even use engine oil, regular old 2% milk works just fine and it’s free if you steal it from the grocery store
 
It’s got a drain plug and a fill plug on both front and rear diff’s. It’s easy compared to some. Even the trans pan has a drain plug.

Easy piesy compared to some.


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Yup. Love it. Wished my ram had axle drains. Best thing since sliced bread.
 
OP probably leases German cars and is a firm believer in their 15k oil change intervals. "It still ran great when the lease was over"
 

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