I want to change the gear oil in my front and rear diff and transfer case.  My first question is how to get the fill plug off.  I tried a 3/8 socket on the front one and it didn't seem to fit really well and the plug wouldn't budge.  What tool do you use to get the plug out.  Second how do you get the lube in the hole since there isn't room to hold the bottle up to it.  Can I tell by looking at the fluid what it's condition is?  I don't know when if ever this has been done in the vehicles past life.  Any other tips would be appreciated.

Ya know, I changed the fluid on the diffs & t-case last year and I only had a problem with the rear diff's fill plug.  So, my tip -- Make sure you can get the fill plugs out before you pull the drain plug.  I had to fill the rear diff through the drain plug -- NOT FUN  

Anyway, I just went through the same thing with the t-case fill plug.  I have no idea why it was so tight.  And I didn't ask how the shop got it loose  

Try some penetrating fluid.  Use a breaker bar if you can.  Some 3/8" sockets or extensions are more square than others; pick the one that fits tightest so you don't round out the hole like I did.  An impact wrench can come in handy.  I don't think I had the impact wrench the first time I did it and this past time I had given away my 1/2" to 3/8" reducer.  I know I've gotten bolts loose with the impact wrench that I couldn't budge with a wrench.

Finally, if you can get it loose, you may want to go with an "Outie" bolt (like I did) versus the "Innie".  I never liked those things.

Good Luck.

I never did get mine out.
I had to fill the diff through the axle breather pipe.
Not much fun i can tell you

my fill plug was the same way, i actually rounded it off with the 3/8" ratchet, so just use a small pipe wrench around the plug.  that is if you don't have a pipe plug type bolt.

and as far as fill the diff, just get a length fo 3/8 or 1/2 vacuum hose and slide it on the bottle of 80/90 which most have a tapered top that yuo can trim to lenth or size of hose you use, the 1 foot of hose will let you position the oil so you can get it all out.  Just start squeezing.

Use an impact to get it off.  Change to an "outie"  bolt.  And, any autopart stores sell a little pump that screws onto the top of your gear oil bottle.  BUY ONE.  Mine stays in the sidekick's tool box at all times.
Brian

Oh yeah, I forgot to mention.  If you had a lift on your rig you would have plenty of room to hold the gear oil bottle upright.  Buy one small bottle to use to fill diffs and other oil needers, and buy a big bottle to fill the little one up... the big ones are cheaper.
Brian

Some of my plugs were tight but nothing a breaker bar couldn't fix. Some people use a fluid transfer pump to fill the diffs, tranny, and transfer case. Mine looks like a giant syringe with a hose on the end or you can use one of these:

"Second how do you get the lube in the hole since there isn't room to hold the bottle up to it."

I've used some clean clear tubing attached to the tip of the bottle and found it pretty effective.

Remeber where this vehicle came from the fastners are all metric!!

I bought the proper tool from the matco tool guy for $10.

Scott

Remeber where this vehicle came from the fastners are all metric!!

I bought the proper tool from the matco tool guy for $10.

Scott

Good tip.  I wonder if Sears sells something similiar.  

Remeber where this vehicle came from the fastners are all metric!!

I bought the proper tool from the matco tool guy for $10.

Scott

It's a freakin' metric hole  That's getting a little carried away now


Do you know the size?  Or is there just a differential bolt "tool" in metric that I should look for?