Front Differential Oil Capacity

Bambusiero

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FYI - Documenting what I couldn't exactly find a number for.

Just changed the front diff oil after 6 1/2 years and 35k miles of mostly low stress road use.
Measured the drain out - right at 4 quarts of nice thick dark gray/green iridescent diff soup.
I'd say it was about like a melted milk-shake, but oil slick flavored - YUMM!

4 quarts minus 8 ounces went back in, so - 80 series locking front differential oil capacity is 3.75 quarts.
My owners manual says 2.65 quarts for locking, 2.80 quarts for non-locking. Not correct I think.
Others on the forum have noted that it took more, but I couldn't find an actual number.

Just a week ago I checked the Birf grease by probing down through the fill hole with a long pipe cleaner.
The grease looked to be in good "Palladium" condition, like soft butter. No sign of liquid or dilution.
So - I take this to mean that about 8 ounces of Palladium Moly grease migrated though the seals into the diff oil over that time.
Those in the know here on the forum say this is normal migration due to the seal design and lack of other venting on the birf side of the seal.

Edit: Also - Really should have changed the diff oil out sooner just to maintain proper lubricant viscosity. Too thick is bad. Might even loose 1-2 MPG? However, a moderate amount of moly content in the oil is no problem, maybe even acts as a wear reducer.
Plus - Double check breather function.
 
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Cruiserdrew

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I think, Toyota lists the minimum amount for this fill. Similar to what they spec for the transmission fill. I agree, it takes close to 4 quarts. The more the better in this application.
 

Bambusiero

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fill til it dribbles out
True, but I used a quart that was supposed to go for the rear diff fluid change. Now I'm short a quart (noo, don't say it) - brought home too few quarts because of what the owners manual says. Another trip to the store.
 

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Having the proper amount is important, but just as much or more is the proper viscosity. Too thick can cause the lube to be thrown away from the gears, reducing cooling, have seen a couple burned up from this. I would change the front at about half that time/miles, oil is cheaper than gears!

Some migration is normal, yours doesn't sound far out of line, but my first check is the breather. If factory, it is a one way valve, out, every time the axle cools it causes a vacuum, increasing the likelihood of pulling grease from the knuckles. Converting to a free flowing breather, some hose and a small fuel filter, reduces this effect.
 
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I did this service awhile back, and both of my lockers took the exact amount of fluid listed in the factory service manual. After filling both of them just a little dribble of fluid came flowing out of the fill plug hole, meaning the fluid was at the level listed in the service manual. Just a suggestion to make sure you haven't over filled them, I'd pull both fill plugs. If they have been filled to the correct level, just a little fluid will come out. If you get more then that flowing out I'd let it drain until it was just level with the bottom of the fill hole. YMMV
 

bajaphile

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I just did my gears last year, so I drained and refilled during the break in period. A few months ago I checked fluid level and it started gushing out the fill hole only on the front... It looked like knuckle grease had migrated in.

I had my stock breathers and never really cared about it...But when I tested them, found they were completely clogged/inoperable. (Made a hissing sound when pulled off the axle too). It may be as simple as that.
 
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I think i used 2.75 quarts, how would you fill more? It came out the fill hole. Force it in?
 

Bambusiero

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Having the proper amount is important, but just as much or more is the proper viscosity. Too thick can cause the lube to be thrown away from the gears, reducing cooling, have seen a couple burned up from this. I would change the front at about half that time/miles, oil is cheaper than gears!

Some migration is normal, yours doesn't sound far out of line, but my first check is the breather. If factory, it is a one way valve, out, every time the axle cools it causes a vacuum, increasing the likelihood of pulling grease from the knuckles. Converting to a free flowing breather, some hose and a small fuel filter, reduces this effect.
Hah! Was thinking overnight I should have said that too (you've said before). Added up above.
My breathers are all tied together with fuel hose to the OEM vent breather gadget bolted to the drivers side fender, under hood.
Tested today - all good. Slow but easy air flow in both directions on both front and rear differentials (long 1/4" tube). The little cap on top pulls down under suction, but does not seal, so air still flows inward too.

VentBreather_1.jpg


Banks videos - Very interesting. More to it than we ever thought.

Maybe YMMV is actually true? Are there different capacity axle housings out there? I filled until the fill hole dribbled, like everyone.
 
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