Just found out that I can get Royal Purple locally and I'm due for new tranny and diff fluid, so I'm thinking that tomorrow will be a good time to change it out. I found a few how-to's with the search, and it sounds like an easy job, I've just never done it and want to make sure I'm not missing anything.

the short version
-tranny
--loosen the fill plug
--remove the drain plug (both 3/8")
--drain the fluid
--replace the drain plug
--use a fluid pump to add 4 qts of fluid/until it starts to come out of the fill plug
--replace the fill plug

-diff.
--same thing, but what size is the hex key?? Everything I found in the search said it was big, but no one know for sure.
--also, is it 1.69 quarts and how exactly do you measure that?

---last, does anyone have pictures -- seeing what I'm getting into would make me feel a lot better. Is there anything else I'm missing??

 

Don't forget the filter.

 

what kind of tranny fluid you gonna use. ill be doing mine real soon too.

 

I'm not talking about the engine oil, although i might do that too, I haven't seen anything about a filter

-------------------------

did some more searching, and found these 2 write ups. I guess my main question now is does anyone have pictures or is there anything I need to look out for.

Lubricant Change
Draining Procedure

Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
Clean any dirt from around the differential drain plug.
Remove the drain plug and washer from the differential.
Drain the fluid.
Filling Procedure

Notice
Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

Important
Do not operate the vehicle at wide open throttle for a minimum of 480 km (300 miles) after refilling the differential with lubricant and friction modifier. Scoring of the ring and pinion gears may result, leading to differential noise.


Install the drain plug and washer to the differential. Tighten
Tighten the differential drain plug to 35 N•m (26 lb ft).





Clean any dirt from around the differential fill plug.
Remove the fill plug, lubricant tag, and washer from the differential.
Fill the differential with fluid:
Fill with approximately 1.6 L (1.69 qt) synthetic axle lubricant GM P/N 12378261 or equivalent
Add approximately 118 ml (4.0 oz) limited-slip differential lubricant additive GM P/N 1052358 or equivalent
Check the fluid level to ensure it is even with the bottom of the fill plug hole to no lower than 6 mm (0.25 in) below the opening.
Install the fill plug, lubricant tag, and washer to the differential. Tighten
Tighten the differential fill plug to 35 N•m (26 lb ft).

Lower the vehicle.


Transmission Oil Drain and Fill Domestic
Draining Procedure

Raise and suitably support the vehicle; ensure that the vehicle is level. Refer to Lifting and Jacking the Vehicle in General Information.
Clean away all dirt and debris from the transmission fluid drain plug area.
Remove the drain plug.
Allow the system to drain.

Filling Procedure

Notice
Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.


Install the transmission fluid drain plug. Tighten
Tighten the transmission fluid drain plug to 27 N•m (20 lb ft).

Clean away all dirt and debris from the transmission fluid fill plug area.
Remove the fill plug.
Fill the transmission with DEXRON®-III transmission fluid, until even with the bottom of the fill plug hole.
Install the transmission fluid fill plug. Tighten
Tighten the transmission fluid fill plug to 27 N•m (20 lb ft).

Lower the vehicle.

 

going to use Royal Purple in the Tranny and diff. I've been looking for any good synthetic fluid, but haven't been able to find any until today. I was going to order some AMSOIL, but unless there is something I don't like about RP, I won't worry about that.

 

Looks like you have everything covered. I trust you are using MaxGear 75w90 in the diff and the royal purple Atf in the tranny.
Been running 75w90 royal purple in my 280zx for a while now and it really keeps things cool and slick.
Plan to use Amsoil atf in the tranny on the c5 starting this weekend, but royal purple has served me well as far as gear oil.
I think you might want to use a touch of rtv to seal the threads on the plugs.
g

 

I always crack loose the fill plugs first just incase I have a hard time getting the fill plugs out. If you drain it and can't get the fill plug out you are stuck.

That being said I have never had a problem getting any of the fill or drain plugs out.

I think the diff has a 10mm allen.

Make sure the car is level for the refill of both, the diff is full when it's level with the bottom of the fill port. Let it drain till it stops as you do not want to overfill it at all. Overfilling the diff some say is part cause for leaks.

GM manual says no WOT for 300 miles after diff service.

 

Good Luck, it's a very easy job, can get a little messy though, BUT it really is a piece of cake.

 

By the way, I changed mine to Royal Purple also. Good Stuff.

Max-Gear in the Diff
http://www.royalpurple.com/prodsa/mgeara.html

Max-ATF in the trans
http://www.royalpurple.com/prodsa/matfa.html

 

My guys recommend using 2 bottles says its better/easier on the diff!
thanks alot
your friend
Sean
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