specified capacity or fill hole???

[jawaring]

I've heard anything from 3-4 quarts for a 4X4 rear differential fill on Tundras.
I know it is different for 4X2's and 4X4's and for trucks with LSD's. Is there also a difference between model years with the same components? I have an '01 V8 4X4 and I've seen 4 quarts posted here in the fluid INFO section, my owner’s manual says 3.7, and the differential takes about 3.1 and then starts to spit it back out. (I assumed the fill capacity would be right at that fill hole) Which is the correct level or does a variance matter much? Should the diff be filled past where it starts to come back out? My experience has been that I can fill it more full than just the bottom of the fill holse because the oil is thick enough to stay in (for the most part) while I pull the funnel out and put the plug in. Obviously I loose a little in the several seconds it takes to switch but this allows me to fill it to specified capacity. Thanks for anyone’s help on this. I'm somewhat of a perfectionist and don't want this thing too full given all the talk of synthetic pushing past axle seals. Thanks!

[JeffD]

If the rear end was dry it would probably take 4, mine usually takes about 3.5 qts. You are supposed to fill until it is level with the bottom of the fill hole. I think there is always a little bit that doesn't drain out.

[nhparrot]

Originally Posted by JeffD

If the rear end was dry it would probably take 4, mine usually takes about 3.5 qts. You are supposed to fill until it is level with the bottom of the fill hole. I think there is always a little bit that doesn't drain out.

FILL DIFFERENTIAL WITH HYPOID GEAR OIL
Torque: 49 N·m (500 kgf·cm, 39 ft·lbf)
Oil type: Hypoid gear oil API GL–5
Recommended oil viscosity:
Above – 18°C (0°F) SAE 90
Below – 18°C (0°F) SAE 80W or 80W – 90
Capacity:
2WD: 3.15 liters (3.33 US qts, 2.77 Imp. qts)
4WD: 2.95 liters (3.12 US qts, 2.60 Imp. qts)

Fill to within 5 mm (0.20 in.) of the bottom of the fill plug.

[jawaring]

Originally Posted by nhparrot

FILL DIFFERENTIAL WITH HYPOID GEAR OIL
Torque: 49 N·m (500 kgf·cm, 39 ft·lbf)
Oil type: Hypoid gear oil API GL–5
Recommended oil viscosity:
Above – 18°C (0°F) SAE 90
Below – 18°C (0°F) SAE 80W or 80W – 90
Capacity:
2WD: 3.15 liters (3.33 US qts, 2.77 Imp. qts)
4WD: 2.95 liters (3.12 US qts, 2.60 Imp. qts)

Fill to within 5 mm (0.20 in.) of the bottom of the fill plug.

Thanks Glenn,

Good info, but how do you measure that? And are you talking about filling to within 5 mm below the bottom of the plug or within 5 mm above the bottom. I know I'm being extremely particular here but I’m curious how exact most people are. I’m also somewhat apprehensive about having synthetic in there now and making sure I don’t do anything to promote seal leaks. I’d rather run the synthetic but am somewhat concerned with Toyotas new TSB about those seals. What are your thoughts? I also used Valvoline SuperSyn instead of Mobil 1. Do you know of any additives in that vs. the Mobil that would be more proned to cause leaking? Thanks so much for your expertise Glenn!

[filhiol]

I don't know how they fill the differentials and transfer case when they are assembling the trucks at the factory but I do know that when I check the levels oil starts pouring out of the fill hole on all of them. I check them completely cold and when the vehicle has not been driven for at least 24 hours. I am beginning to believe that they fill them prior to installation by standing them on end with the fill hole being up.

[jawaring]

Originally Posted by filhiol

I don't know how they fill the differentials and transfer case when they are assembling the trucks at the factory but I do know that when I check the levels oil starts pouring out of the fill hole on all of them. I check them completely cold and when the vehicle has not been driven for at least 24 hours. I am beginning to believe that they fill them prior to installation by standing them on end with the fill hole being up.

That's a great point,

Mine did that too so I figured the mfg fills them before they are assembled on the truck. I can picture the differential sitting face up with the exact amount put in before they are set vertically on the truck.

[nhparrot]

Originally Posted by jawaring

Thanks Glenn,

Good info, but how do you measure that? <snip>

Fill till it starts coming out a litle is the easiest way.

Ken aka KLS is much more knowledgeable about oils than me, mybe he will cime in here.

[akauth]

Originally Posted by filhiol

I don't know how they fill the differentials and transfer case when they are assembling the trucks at the factory but I do know that when I check the levels oil starts pouring out of the fill hole on all of them. I check them completely cold and when the vehicle has not been driven for at least 24 hours. I am beginning to believe that they fill them prior to installation by standing them on end with the fill hole being up.

Actually, I overfill my diffs slightly also. That way I know they are full (and with synthetic). I fill my rear diff and transfer by having the vehicle face downhill and the front diff when it's facing uphill. I give one last hard squeeze and then put the plug in before it (or much) comes gushing back out. (Too, I always put the fluid in the hot sun for a couple hours to make it flow the best - and smell the worst!)

This elevates the drain hole higher relative to the rest of the diff (than normal). So if you check my components "on the flat" fluid will always drain out. You don't need to stand them on end at all. Just have the pumpkin leaning a little lower than normal (or fill them on an incline like I do).

Alan

[doctormdds]

I fill mine until the oil starts to come out of the hole while the vehicle is on level ground. I get in no hurry to place the fill plug as I figure the oil level should be even with the bottom of the fill plug hole. While I'm certainly no expert on this subject, I figure that a little short or a little over full will never make any difference. Also, I use Mobil1 and never a problem on my 2001 4x2.

[HOTundra]

I changed the LSD differential fluid yesterday with Trans X modifier and Mobile 1
synthetic. Found metal shavings on the magnent, but i believe it may be part of
the assembly (First diff. change)! Bolts came off easy and no leaks.

[doctormdds]

Originally Posted by HOTundra

I changed the LSD differential fluid yesterday with Trans X modifier and Mobile 1
synthetic. Found metal shavings on the magnent, but i believe it may be part of
the assembly (First diff. change)! Bolts came off easy and no leaks.

It is totally noramal to find metal shavings on the magnet at the first change of the differential fluid. I too was alarmed of this when I changed mine the first time. Then, thanks to this group, I found that it is to be expected.