Front Differential fluid?

[RyanbabZ71]

Well i have decided to change the front diff fluid before fall/winter.  I have over 30k.

 

What fluid are you guys running?  I know it is 80W-90 but what brand (synthetic?)

 

Also anyy tips/tricks?

 

Thanks itll probably be a wk or 2 before i do it

[MountaineerTom]

Valvoline non-synthetic.

 

Take that big skid plate off to do it.  Makes it super easy.  Not much to it other than draining and refilling.  

[RyanbabZ71]

how much does it hold?

[MountaineerTom]

I don't remember off hand, and I just did it a few weeks ago.  I think I bought 3 or 4 quarts, but didn't use it all.  As per the owners manual, fill it until it runs out the fill hole.

[99silveradoz71]

Believe I used valvoline non-syn as well.  Just over 2 bottles if I remember right.  I'll have to check the garage to be sure.  Did the mobil 1 for the rear.

[MakoMike]

???  Okay, tell me again why it is not recommended to use Mobil 1 in the front? Seems like if it comes with Synthetic in all the other driveline components, why settle for less in the front alone...

[GnatGoSplat]

???  Okay, tell me again why it is not recommended to use Mobil 1 in the front? Seems like if it comes with Synthetic in all the other driveline components, why settle for less in the front alone...

Cuz it costs more, that's why!

 

And the front doesn't need synth because you don't use it but a fraction as often as the rear.

 

BUT there's no harm to use 75W-90 synthetic.  The only harm is a lightening of your pocketbook!

 

I'm gonna go ahead and put 75W-90 synthetic in mine.

[99silveradoz71]

???  Okay, tell me again why it is not recommended to use Mobil 1 in the front? Seems like if it comes with Synthetic in all the other driveline components, why settle for less in the front alone...

Not sure if there's a "real" reason.  The guy at the local parts chain(Murray's) here said that it was non-synthetic from factory, so it should not be changed.  I believe they only sold the synthetic in the weight for the rear too...that I think was his concern, the weight difference.

[Suburbanite]

My GM factory service manual calls for the same weight front & rear, & that's what I used, only synthetic: Castrol Syntec @ $6.??/qt. Same set of service manuals list 2.6pts & 4.5pts capacity for 1/2T & 3/4T front diffs, respectively. There are 2pts (pints) per qt (quart). Here's a FYI: Most (computerized) parts counters should be able to provide capacities based on vehicle info.

 

Forgot to mention the info above applies to a '95.

[Big Bert]

Ryan have you changed it yet? Does anyone have any pics of the drain and fill plugs? I want to make sure I get the right ones.  ??? I have 40,000 miles and I am over due for the change. Thanks for any help

[MountaineerTom]

Ryan have you changed it yet? Does anyone have any pics of the drain and fill plugs? I want to make sure I get the right ones.  ??? I have 40,000 miles and I am over due for the change. Thanks for any help

Here you go.  The top is the fill plug, the bottom is the drain plug.  

 

[MountaineerTom]

Oh yeah, remove the skid plate to make it easier to get to.

[Big Bert]

Hey thanks a ton for the great pic. That makes things pretty easy for me. But I do still have another Q. I hope this isn't a really stupid Q but here it goes. What is the easiest way to put oil in a horizontal hole.  

[RyanbabZ71]

nope havent done mine yet (probably oct 11th since i have off)

 

I am stilllooking for Mobil 80W-90 gear oil to no avail

 

Also on gear oil the container isnt like regualr motor oil.  It has a skinny neck which you can out in the hole.

[MountaineerTom]

You can buy a hand pump that screws onto the bottle, and then pump all the fluid into the diff through a hose.