Rear Differential Oil Volume

Happy New Year!

Yesterday I did my first front and rear differential oil change on my 2024 SR5 4Runner with 27,000 miles on it. I am curious if I need to be aware of anything as the REAR diff took well over 1/2 quart more oil than Toyota says it should take.

In the research I did before getting into the work (YouTube and 4Runner forums) I found that everyone said to fill the front and rear diffs with oil until the oil begins to trickle out of the fill hole and that this should happen somewhere around 1.5 for front diff and 2.9 for rear diff for my model without a locking rear diff. The Toyota manual (image attached) gives specific volumes of oil for the front and rear diffs.

When I filled the front diff it took about 1.5 qts before it started to overflow and oil came running out. When I filled the rear diff I pumped in 3 full qts and no oil had started leaking. I opened a fourth quart and pumped in half of that before the oil started flowing out of the fill hole. So my question is: Do you think it is better to follow the Toyota manual and measure out the exact volume of oil (2.9 quarts for rear) and pump just that in, or go with the method it seems everyone is using and just keep pumping until the oil trickles out of the fill hole? I have read in some forum posts that too much oil can introduce leaks. Any insight is appreciated! This is my first time doing this job and in hindsight I wish that I had drained front and rear diff oils into designated containers as I just drained the oil into a large pan with other oil already in it and had no way of measuring how much came out. Live and learn!

 

As long as you were on level ground I wouldn’t worry about it.

 

Great point! I forgot to mention that, but yes, I was on level ground.

 

I went thru same thing and added more till it overflowed out fill plug. Not sure if correct but I have always just filled until overflowed on my Toyota diffs.

Quoting @3JOH22A on pinky test from another post on amount of fluid in diff:

reach in the fill port with your pinky. Rule of thumb (pinky?) is if you can get oil on your pinky, the oil level is within service specification (fill port +/- 5mm).

 

Why?

 

Yea he should of waited til 30K. Lol
OP I would do the same thing as you. I call it preventative maintenance.

 

Lmao. “Pinky test”. I thought only I did that. I get paranoid and just need reassurance that it is full. Happy new year to ya

 

Because I purchased it pre-owned and it was a rental before. The peace of mind that it's been done is worth it to me vs squeezing a few thousand miles out of the OG oil to hit the 30k mark.

 

Fair enough.

 

Fill till it starts to flow from the fill valve.

 

it’s due at 30k if you actually do maintenance on your vehicles. And for a 10 min job why not.

 

I was on level ground, base sr5 4wd, and it took exactly 3 quarts.. interesting yours took a little more.

since it’s very easy to crack open the fill plug, do the “pinky” test and see if you just get a little trickle, or if it drains out. I know you said you were level, but always double checking is good.
And I have a buddy of mine, he also just recently got a 4Runner that was a previous rental. I went with him to inspect it, scanned it, pulled fuel trims, etc. both banks short and long term trims were around 0.1% - 0.5% after a 30 min drive. So motor is happy.

his was running like a top, clean skid plates, little dings or scratches, but it’s going to happen anyways.

we both plan on doing a drain and fill on our trans soon, since we’re both closing in on 30k. Some people say the stigmas of rentals are bad. But most people on here beat on their 4Runner harder than any rental did down the highway. (Rock climbing, mud holes, lifting without replacing UCA, putting driveline in angles it shouldn’t be in.

enjoy your truck and it will surely take care of you!

 

The diff holds more than listed but more doesn’t mean better.

 

Meh, the level of the fill plug isn’t going to allow you to overfill it enough to be detrimental. Everyone uses the ‘fill to overflow’ method.

 

I call it a waste of money. These are not clutch pack LSDs. You should be able to 100k unless you have forded water or otherwise subjected your 4Runner to severe duty.

 

More than likely fine but not always. Banks did some testing on excess fluid and you sometimes end up adding more heat as the gears work the fluid.

 

Exactly. I double the "recommended" service interval. In the three times I've changed mine (currently 190K) I still ask myself "why"? every time. Fluid comes out relatively clean, and almost zero metal on the plugs. But, I'll still do it every 60K for "preventative maintenance".

 

Good way to need a rear end waiting that long.

 

Is the 4Runner diff less durable/reliable than any of the dozens of cars/trucks I've owned over the last 58 years.

 

In the old days of clutch pack LSDs frequent changes were warranted due to contamination from the plates themselves glazing the clutch plates. There is nothing but gears and bearing as well as the mechanical locker to lubricate. A differential does not generate a significant amount of contamination.

 

How often do you see a truck with diff issues due to not changing the oil? Probably never.

 

I have not been that lucky. My rear diff oil was very gray, and the magnet was loaded up with plenty of metallic sludge both times I changed it (approximately 30k intervals). I’m probably due for the third change soon.

However, front diff and transfer was golden honey when I changed them. But I’ve only changed those once.

 

fill it up until it trickles out, then youre good.

 

Listen, don’t explain yourself. There are people on here who will only do 10k mile oil changes. I do them every 5k. For the $50 it costs me to do mine it is peace of mind. Not to mention 10k mile oil changes are for only people who drive daily and for greater then 50 miles. But whatever. There are people on here who always have to be right. Do whatever gives you piece of mind. I totally would have done what you did. Heck I’d even change the front diff and transfer case.

 

If the diff really took more oil than it’s supposed to then maybe you have a screwed up seal and oil is getting into the axle tube.

 

oil is supposed to go into the axle tube that is why there are axle seals at each end

 

I did front and rear diffs . Transfer case is next!

 

pretty sure oil is supposed to go into axle tube from rear diff. And any problems like that seem highly unlikely as the car was first put on the road on Jan 5, 2024 and looks new. Not even marks on the skid plates or anywhere on the underside.
My only reason for changing the oil a bit early is given the mileage.

 

Oops. Ignore that post then. I thought the seals were closer to the diff.

 

Regardless of mileage you could have an improperly seated seal from the factory. It was an issue with some Tacomas.