Rear Differential oil change guidance/advice

I drive a 2017 4Runner 2wd Limited. Specs say the rear diff should take 2.9 quarts. So I bought 3 quarts, parked on level ground, and did a drain and fill last week. I wish I had measured how much fluid I removed, but didn't. I filled it with all 3 quarts of Valvoline synthetic 75W90. I was expecting it to overflow from the fill hole at the end of the 3rd quart but it never did.

I drove it for a week, not really noticing any problems, but my OCD kicked in not knowing if the chamber was full. So I bought another bag and ended up adding about another 0.3 quarts before it spilled out the fill hole.

My 2 questions are these:
1. Anyone have any experience knowing why my differential chamber took 3.3 quarts of oil, when the manual says should be 2.9q?
2. Did I do any damage to the differential gears by running it ~0.3 quarts low for a week?

Thanks

 

You’re not the first person to run into that, not sure why that discrepancy is but don’t worry, I guarantee you’re fine.

But I also relate to your stress about it.

 

Just follow the amount Toyota lists. More isn’t necessarily good because it could cause aeration.

 

I also use Valvoline for my front and rear diffs and use the “squeeze bag” that makes it so much easier to fill the diffs. That said, I have noticed that the bag does not necessarily fully empty while squeezing into the fill hole so I drain the spent bag into an empty bag as I go. You may have had enough fluid hiding in the spent bags to be off by a little.

I recall my rear diff taking a little over 3 qt bags before it overflowed…

Since you were only off by 1/3 qt., your diff is fine…

Cheers,
Bob

 

You are fine. Just make sure you can see the level. Some of the manuals show a picture of the diff with where the level should be. If you use the plastic bags you can easily control how much you put in until you can see the level. I can't remember how many qt's I used, but it took forever to fill in because I used the bottles and not the bags. I then did it with bags on the taco and it was so much faster.

 

Id be more worried about a 2wd 4runner.


https://www.4runners.com/threads/rear-differential-oil-capacity.21788/


Youll be fine bud. Happy adventures out there.

 

1a. The axle housing is a multi-piece weldment. The differential inside has many cast- and forged parts. The mfg tolerances easily add up to 10% fluid volume variation. Remember your 4Runner is a mass produced vehicle, with one rolling off the line roughly every 1.4 minutes.

1b. The service manual specification is +/- 5mm from the fill hole. 0.3 qt over the width of the whole axle housing equates to less than 5mm level change. You didn't have to add the 0.3 qt.

1c. The axle angle changes a bit when fully drooped, so the fill hole level is slightly different when your 4Runner is on a two-post lift at the dealer vs. on the ground.

2. Damage doesn't occur until it's down to 2.0 quarts.

 

thanks all! much appreciated!

 

I did mine a couple weeks ago and had the same issue. Filled with 3qt of Redline 75W85 and it didnt drip out. Called it good as it was already the amount called for in the manual. Yes I stress a little, but I forgot about it until this post. Thanks