Differential Oil Change Question

[Sachry]

So I am going to change the oil in my differentials. My question is on the rear differential, the chilton manual says use 75W-90 Synthetic Axle Lubricant, but for the capacity it says the following:
- 8.6 inch axle = 2.2 quarts
- 9.5 inch axle = 2.75 quarts
- 11.5 inch axle = 3.2 quarts

What is that size based on? Is it the diameter of the ring in the gear? Is it the circumference of the axle? A little confused by it.

Oh yea, and my truck is a 2007 chevy silverado 1500 LT extended cab with a 4.8 L four wheel drive.

Thanks

 

[Rhymingmechanic]

Those are ring gear sizes. I'm going to bet yours is the 8.6.

 

[Jim Allen]

1500s often have the 8.6-inch ring gear axles but some half-tons also have the 9.5 inch. The 8.6 has a 10-bolt cover and the 9.5 has 14 bolts.

 

[Boomer]

And since you'll need three quarts for either, just fill it til it runs out of the fill hole and you'll be fine. And always make sure the diff vent is open to the atmosphere and not clogged.

 

[Sachry]

Awesome. Thanks for the info. Just what i needed.

 

[dsmith41]

Diff vent???

 

[mechtech2]

Auto and manual transmissions, transfer cases, and rear ends have a little vent [always on top somewhere!] so thermal expansion of air and fluid won't cause leaks out of the seals/gaskets.

Like Boomer said, your gotta get 3 qts anyway, and the fill hole is how you set the level.

 

[MetalSlug]

any tip on how to clean the vent ? some it clog with dirt or grease. just spray some brake carb cleaner over it and wipe it down with a clean tower ?

 

[mechtech2]

There is usually a metal crimp cap on it, or for some trucks, a hose that goes way high [off road dirt and water].
They hardly ever need service,but you are being smart to check it.

See what you've got, and proceed with common sense.