Need Clarification on REAR DIFFERENTIAL OIL CHANGE

[SyberTiger]

Okay, I understand the process is very simple.

1. Remove the FILL PLUG. Oil may or may not come out from this hole. Some folks report oil comes pouring out.

2. Remove the DRAIN PLUG. Drain the oil.

3. Install the DRAIN PLUG. Tighten to 34 Nm (25 ft. lbs.) .

4. Add 3.25 - 3.5 pints (chart below) of 75W140 Synthetic Gear Oil in FILL PLUG opening to the bottom of the hole. Include at least 4oz friction modifier if you have a limited slip differential...I do not as my axle code in the door is 46.

5. Install the fill plug. Tighten to 34 Nm (25 ft. lbs.)

6a. For roll stability control (RSC) equipped vehicles, remove the rear wheel speed sensor plug.

6b. For non-RSC vehicles, remove the rear wheel speed sensor.
---- 6b-1. Disconnect the rear wheel speed sensor electrical connector.
---- 6b-2. Remove the bolt.
---- 6b-3. Remove the rear wheel speed sensor.

7. Add one pint of fluid into speed sensor hole.

8. Put the sensor back by reversing step 6.

The part that is unclear to me is that the vast majority of folks do not seem to be doing steps 6 through 8. Does this mean a lot of you are running a pint low?

I have RSC on my vehicle but it doesn't seem to matter. Extra oil needs to be added regardless. Does anyone have a pic of the differential with these sensor plugs where you would add an extra 1 pint of oil?

 

[roush9799]

I wouldn't worry so much about the pint. If you do a complete rebuild and all the oil is off all the parts and such, maybe then it would concern me. If you take it in for service and they check the rear oil, they'll remove the plug to check it. WHen I changed mine I had it jacked up, I got a bit more in this way. I had a hose in the fill hole, and when I took the hose out I hurried up and put in the plug, so I know there's some extra in there. Even up to the hole, there should be plenty of oil in there to be sloshed up around all the gears and get to the bearings and not get hot.

 

[iBrent]

I have RSC as well and I added the extra pint. It's actually not that hard.

Step one, get a mirror, this kind:

http://www.sears.com/craftsman-2-1-8-x-3-1-2-in-mirror/p-00904098000P?prdNo=2&blockNo=2&blockType=G2

or equivalent.

Remove the spare tire. Jacking up the rear is not necessary unless you need to in order to level the vehicle.

Use the mirror to look at the top of the diff near the front and off center towards the driver's side. You'll see a black rubber plug with a single bolt. Remove the bolt, then use a flathead screwdriver to assist in removing the plug. It has a seal around it so it might be a little tough to remove.

Using the mirror, insert a rubber hose into the hole going as far down as you can, that way it doesn't pull out while you're pumping. Pump in the extra pint. Remove the hose, reinsert the plug, tighten the bolt. The manual will have the torque spec but good luck getting a torque wrench in there.

It didn't add much extra time so to me it was worth it. Next time when you remove the fill plug you'll definitely get a pint coming out, I always do.

 

[SyberTiger]

Thanks iBrent.

I just followed the procedure as outlined in the OP. The fill plug is 3/8" drive and the drain plug is 3/4" drive. I don't have a 3/4" drive wrench so I bought an adapter kit at Harbor Freight for $3.99. The 1/2" to 3/4" drive adapter is what I used for the drain plug.

I didn't jack up the vehicle. I followed iBrent's advice and removed the spare tire. This helps out greatly. There isn't very much room to put great force on the wrench to take out the plugs. I didn't have enough room to get my breaker bar in there primarily because the vehicle was not on a lift. Not only was the length of the breaker bar a problem but also when I put my 1/2" to 3/4" or 1/2" to 3/8" adapter on the breaker bar there wasn't enough clearance to stick the adapter into the plug hole. I ended up just using a 3/8" drive wrench for the fill hole and a 1/2" drive wrench with my 1/2" to 3/4" adapter then using a hard rubber mallet to beat on the handle. It took quite a bit of force to get those plugs to budge. It would appear that the factory used Loctite Red on the fill plug threads and pipe fitting putty on the drain plug threads.

I used about 3 turns of teflon tape when I put the plugs back. I did not torque the plugs as there isn't really any practical room to get a torque wrench in there. I pretty much just put them back very tight at approximately that same depth I found them at.

Adding the extra pint of gear oil through the sensor plug was rather easy. As iBrent suggested, a mirror goes a long way to locating and understanding what/where the sensor plug is. Because I had the spare tire out of the way I was able to get a huge hand mirror up in there. I took a picture. The mirror is above the differential so the image is a reflection off the mirror showing what the top of the differential looks like.

The small bolt holding the sensor plug in place is 3/8". There isn't much room to maneuver wrenches on top to the differential but I managed without too much difficulty. Pumping the extra pint of gear oil went smoothly. I used Amsoil 75W-140 SEVERE GEAR Synthetic Extreme Pressure (EP) Gear Lube. The plug is made of a composite plastic type material and there is a rubber O-ring around the stub that sits inside of the hole in the differential. Putting the plug back in place wasn't too difficult. I did not torque the small bolt but made sure it was tight.

When I took out the fill plug a fair amount of gear oil came out. I'm not sure if it was a full 1 pint that came out or not. When I removed the drain plug and drained the oil I was somewhat disappointed that the oil did not look dirtier. With 125K miles on the vehicle I somewhat expected the oil to be black. For the most part it looked very clean. When it was all said and done it would appear that my differential took closer to 3.9 pints of gear oil.

Thank you to everyone who chimed in on this thread.

p.s. A couple of weeks ago I replaced my rear wheel bearings. What a chore! Anyhow, I didn't have time to inspect my seals on the differential while I had the knuckle/spindles assemblies removed from the half axles. While I was changing the gear oil today I had the chance to inspect the seals. I was pleasantly surprised to see that the seals had no leaks.

 

[jstorm001]

I was thinking about changing mine also I'm sure it was never been changed my Axle code is D4 does anyone knows what type of axle it is?

 

[SyberTiger]

I was thinking about changing mine also I'm sure it was never been changed my Axle code is D4 does anyone knows what type of axle it is?

Click HERE to look up your axle code. You have a limited slip differential therefore you will need to add the friction modifier.

 

[jstorm001]

Thank you!