All,

I noticed that oil was leaking from the rear diff (visible oil around the drain plugs) I took it to the dealer to see what they could do for me (still under warranty). I got news that the diff plug in the rear diff has a tendency to get loose per the Service Advisor of my local dealer. This is supposedly common with the 4Runner FJ and Taco off-roading crowd. They replaced the gasket and added additional sealant to prevent it happening again. Please check your diffs if you offroad even occasionally. Overall Toyota handled this pretty well... The parts and labor were done under warranty.

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Unless I have lost all special awareness (long day and its a sideways photo) I think that's the fill plug.

I also thought the oil level was just below that when full. considering it would be next to impossible to just pour in more oil then the level of the fill plug I assume the seepage is from the "throwing" of oil off the gears and from general driving......Any one got a video of a differential in motion with a clear case.......curious on how the oil behaves.

YouTube here we come

Not a leak but a weep. Common cause is heat and cold.

Could be the fill plug. Not too sure. I'm just relaying the info from the SA.

New gasket and additional sealant?
This will certainly cause an issue later, when the vehicle is out of warranty.


I would of demanded nothing short of a new axle....



J/K

Was hoping for a new Prius lol

They don't have a tendency to come loose unless they aren't torqued properly or the crush washer isn't replaced after loosening.

Service Advisor = Oxymoron.

I guess I'm glad you posted this. Mine has been OK for 3 years and 40K miles. I changed the diff oil last week, cleaned the plug, put a little anti-seize on it used a new gasket and torqued it to the setting.

Now I will be checking this, thanks for the extra maint. task for me.

If you put anti-seize and torqued it to specs, it's very possible you went right past the torque specs due you putting anti-seize on the threads!
Reduce torque value when using anti-seize.

YMMV

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Well I've never touched the diff, nor did anyone else. Maybe it's just a freak thing?

did somebody else touch the diff?

isn't the first diff service at 30k (under severe service)? Did that happen?

just asking because @Antman is right... it wont come loose if the crush washer is crushed and its torqued correctly...

Okay, first things first, that is indeed the fill plug. Oil around it does not necessarily mean that its leaking, as dirt and crap on the back end of the diff will act like a wicking material and soak up any oil that's around the plug itself, this is pretty normal. A good spray-down with brake clean and a quick wipe of the back end will get rid of the oil.

Usually you'll see this happen when someone does a diff service/check, which should be part of the maintenance at, IIRC, every 30k, at the dealership. Basically, they pull the plug, see if a slight drip comes out of the fill hole, and make sure the oil is not milky (which means someone's been fording rivers/streams without a diff breather relocation tube!).

Because the diffs are usually overlooked by most owners, its should ALWAYS get a new crush washer in there whenever the plug is pulled. This will keep it from leaking.

Now, you will still have some oil seepage, mostly from the plug since the hole is dripping oil when you put it back in there. That little bit of oil on the plug and crush washer is plenty enough to wick all the way around the plug, exactly like your photo shows. It may take a few weeks to months, but it will do this nonetheless. Nothing at all to worry about.

One other thing here, and this is why the dealership says its a "common thing with the offroading crowd", is the fact that when offroad, vehicles will see different angles, such as going uphill and downhill (which would affect the front diff), that puts the oil level directly over the fill plug. When combined with heat from gear friction, as well as some oil getting into the breather, a slight amount of pressure will build up in the diff which could potentially push a bit of oil through the threads of the fill plug, and will bypass the crush washer if its not been replaced each time you check it.

These are all such slight amounts of seepage that it would literally take decades to really affect the oil level in the diff!

Oh yeah, there is no reason whatsoever to have sealant put on the fill plug for this issue! IMHO, this is just a bandaid on a problem that doesn't exist, and the service dept is just appeasing you to get you out of there.

Next time you're in a parking lot, take a look at all the rear wheel drive vehicle's diffs, I'm willing to bet that most of them over 3 or 4 years old will have the oil spot on their diff.

I just changed my diff fluid in my '87 truck about a month ago, cleaned it all up with brake clean when I was done, wiped it all down, used a brand new crush washer, and with the dust around here (I haven't driven the truck in wet conditions for years so its always dusty underneath), I have a small oil stain just like yours, both front and rear.

It is common at some service centers to pull the fill plug to check fluid condition/quantity. Not saying that happened, but some places do that....

normal engine oil service would include checking the drive train fluids. with gear oil just a drop will create that picture you displayed. so if oil was on the plug threads that would explain the look you got on the diff. if it was leaking it would run down from the plug and look wet. also if it was topped off that would also show like that.

using thread sealant on the threads is used on some diff plugs. plugs that use a seal washer would not require sealant as the washer does it.

over torque can cause leaks with the washer plugs.