Rear differential takes 5.5 quarts to fill up, owners manual disagrees.

I own a 2002 sequoia RWD sr5/with the tow package (i post here because sequoia forum has no traffic and it’s essentially the same truck )

i decided to change my rear differential fluid out. I filled it up to the fill hole until fluid started dripping out, that was at 5.5 quarts. Owners manual tells me it should have only taken 3.9 quarts. I looked around at different forums and can’t find anyone that’s in the same situation as me. also the fluid that drained out was 5.5 quarts.This is my first time draining and filling diff as the owner of the truck.

What’s with this discrepancy, everywhere i look says around 3.9 quarts. Should I be worried?

also is

$39 75w-90 GL-5 Limited Slip, Ultra Long Drain 500k Miles, Manual Transmission, Gear/Differential Lubricant (1 Gallon)

75w-90 a good viscosity to use for my specific truck?

 

That suggests that the last guy may have overfilled it. With the truck on a level surface, add fluid until it starts to drip out the fill hole. That's how much it takes.

 

Please read my whole post. That is exactly what I did. I filled it, yes, on a level service, and yes, until it started to drip out of the fill hole

my question is why is there so many different answers with how much fluid it should take. Why is there this discrepancy between the 2002 owners manual and how much fluid it actually took. Every repair manual says something different but not a one of them says anything close to 5.5 quarts and I’m positive it’s the original differential.

 

It takes what it takes. Drain hole is on the bottom. Fill hole is on the rear of the housing around halfway up. If you use those two openings, you Gucci. No idea why or how yours takes 5.5qts.

 

x2

Don't get hung up on the numbers in the manual. There are variations in volumes even inside the manual for your year, depending on what's in the pumpkin (open vs. closed diff), the volume of metal linked to each will be variable. Say someone had a new rear diff cover welded on. Or replaced the axle housing with one from another vehicle. There's any number of reasons. But generally speaking, that top hole should be setup in a way that ensures the diff is adequately coated in lube if you fill until oil comes out of the hole.

 

Do you mind taking a picture of your differential cover? Do you know if that was ever replaced due to rust? I recall someone on here had theirs leak and the shop made a custom looking one that was bigger than OEM/ Dorman one.

 

Theres no way mine would of been replaced due to rust. My truck is 100% rust free (and im very thankful for that, glad to live in a southern state lol) Everything looks original as far as my truck

 

As other people have said: level surface and fill it until it starts to weep out of the fill hole. It’s a lot worse to overfill diffs than to under fill them a little, so no need to worry about getting every last drop in there…. let it weep out until it stops and then tighten that fill plug.

 

You didn’t have the rear of the truck significantly higher than the front by chance? Thinking gear oil could fill around the pinion if you really had the back up high resulting in overfilling. 1.5 qts seems like a lot to be off spec. Any chance you miscounted and it’s 4.5?

Not trying to insult you in anyway - just running through possibilities.

 

Put a pan under it and remove the fill plug and let it drip for an hour or so, with thick oil you can get a lot in, even though oil level above the opening. It will drain back to the proper level. All my BMW M/C's have that arrangement on their gearboxes. I pour it in and let the excess drip out. It takes a while to do, especially if it's cold. The final answer is, fill it to the top of the threads. It's just physics, on a level surface, given time it will find the proper level. Don't overthink it.

 

Thanks this is the best advice so far. Will definitely be doing that when i have time

 

The Double cab and sequoia have a wider rear axle, i remember measuring mine and i think its about 1.5" wider per side or about 3" wider overall. This is from longer tubes on each side of the pumpkin, and also requires longer shafts for these wider rear ends. This wider rear end no doubt is going to take a smidge more oil to fill versus a narrower rear end in the extended cabs.
I dont think its a quart worth but i could see it being a pint maybe, maybe its two pints who knows.

 

It's about .75" per side, 1.5" total, but we filled mine with roughly 4 quarts after a full drain and cleaning of the housing. 5.5 seems way over.

 

I took your advice and pulled the fill plug off, on a level surface, and let the truck sit for about an hour. Roughly 1/4 a quart ended up draining out, leaving my rear differential at about 5.25 quarts, if my math is right. I’d say that helped ease my mind a little bit. Still a little weird how I can’t find any information that aligns with my experience, and I scowered the whole internet looking.

Hopefully someone can chime in about my other question. If

$39 75w-90 GL-5 Limited Slip, Ultra Long Drain 500k Miles, Manual Transmission, Gear/Differential Lubricant (1 Gallon)

75w-90 is an appropriate viscosity for my truck. (2002 RWD sequoia with the tow package). Although the owners manual called for straight 90, it was next to impossible to find, so I thought the next best thing would be 75w-90. (I mean hey 90 is still in the title, right? I might be wrong with how I think oils work so call me out if im a dumb dumb)
I went with Valvoline brand, from this picture.

 

I think the level and viscosity are good. No more worrying about this, is my opinion. .