Topic: How to: Manual Transmission and Limited Slip Differential Oil Change

[S.P.]

Changing the fluid in both transmission and differential is very easy. Hardest part is cleaning up the mess, and having to deal with the smell of the gear oil. That stuff is foul! 

Summary of tools I used:
3 qt 75W-90 transmission fluid (GL-3) (2.75 qt required)
1 qt 75W-90 differential fluid  (GL-5) (1.1 qt required)
Ratchet with 10mm socket, extension, and universal joint
10mm box end wrench
10mm Allen wrench
15/16 open end wrench and socket
Torque wrench

You may also need:
4 oz. LSD additive (If it doesn't already come premixed into the diff fluid)
4 washers (Replacing the washers on the drain and fill plugs are recommended, but I don't bother)


Properly jack vehicle up at the four required points. You can see where someone cracked my fender doing it improperly:



This is the transmission cover panel; It needs to be removed using 10mm wrenches. The exhaust kinda gets in the way:



Remove transmission fill plug with a 15/16 wrench. Notice the case reads 75W-90 GL-3:



Remove transmission drain plug with a 15/16 wrench. Once drained, reinstall and torque to 27 ft-lbs:



Fill transmission with 2.75 qt of fluid. For pumping the oil back into the transmission and differential, I highly recommend using a hand pump like this one:



DO NOT USE THIS:



Reinstall transmission fill plug and torque to 27 ft-lbs. Reinstall transmission cover panel and use german torque (sorry, couldn't find a torque value).


Remove differential fill plug with 10mm hex key:



Remove differential drain plug with 10mm hex key:



Notice metal particle buildup on magnetic top of drain plug:



Once drained, reinstall drain plug with german torque. Fill differential with 1.1 qt of fluid and reinstall fill plug with... you guessed it... german torque! Good luck, and enjoy!

[Kelu]

For European folks who can't find Royal Purple products   I used Motul 90PA for our diff because is especially for clutch type differentials as we have:

Motul 90 PA
Extreme Pressure Lubricant for Limited Slip Differentials (LSD)

TYPE OF USE
Specially formulated for limited-slip differentials : Racing cars, Passenger Cars and Industrial applications.
Special formula includes a friction modifier for clutch-pack or plate type differentials to prevent dragging of discs.
All types of differentials with or without limited-slip systems operating under moderate to heavy loads at variable speeds.
For BMW rear axles with limited-slip differential, use MOTUL HYPO SYNT LS.

PERFORMANCES
STANDARDS:
API GL4 and GL5
MIL-L-2105D

Extreme pressure lubricant for an efficient anti wear protection.
Very high lubricating properties to reduce friction and enhance component life.
Compatible with all types of seals.
Anti-corrosion, Anti-foam.

I can confirm no more clunk noise, I'm about to change the gear oil and I will be using Motul Gear 300

[Critterman]

Motul is the French product that smells like coconuts right?

[Kelu]

Motul is the French product that smells like coconuts right?

Dunno what motul are you referring but Motul is a strong brand, they started to release oils for each car brand to kick the manufacturers in the balls no more bullshit from dealership like "generic engine oils are not good for your car, you should get oem oils"

Talked with the guys from National Rally Championship and many of them are running Motul and they did test all oils in their competition/practice/daily drivers.

[NormSky]

Yeah, Critter and it taste like duck liver. 


Don't why more Motul products are not sold in the states.

[Imaj]

Motol is sold in most U.S. European high end performance shops. I use Motul brake fluid religiously and get it here in Dallas.

[Kelu]

Don't why more Motul products are not sold in the states.

Tell us, the EU guys, about Royal Purple products 

[Arabas]

Thx a lot SP!

Kelu i checked RP site and they have a distributor in Italy.
We should email them and ask an offer.

smoothier shifting is something i had been looking for some time now...

[DeepBlueGXP]

did you add the rear diff additive? 

[S.P.]

That's not necessary. Max Gear has limited slip additive already mixed into the oil. Some folks have added additional additive to it (thats a lot of adds), but I didn't want to take the chance of having too much additive in there.

[Imaj]

I saw RP Synchromax High Performance Manual Transmission Fluid. Woiuld that work on a Manual Sol? Thanks!

[S.P.]

I wouldn't use that. The product description for RP Synchromax reads:
Synchromax is recommended for manual transmissions that specify an automatic transmission fluid.

The manual transmission for the Kappa calls for 75w-90 gear oil. From what I've read, Synchromax is a lighter weight fluid than that (somewhere around 0w20).

[Arabas]

SP, so you used the same product for both the tranny and the diff?
or these two are two different products?

[S.P.]

Yes, I used the same product for both tranny and diff. Both call for 75w90 gear oil, so I used RP Max Gear in both. I was afraid that part of my original post was going to be a little confusing. I'll edit it for clarification.  

[Imaj]

I see S.P. Thanks!

[NormSky]

I used the asame weight for both. Some say even lighter weight for the transmission with even better results.

[Imaj]

Damn! With Royal Purple 75w-90 Max Gear at almost $19.00 a bottle, this stuff is not cheap.

[spartan]

If you buy a 12 pack on amazon it brings the price down to the low teens.  I am going to change out the fluids on another vehicle which uses 75W-90 as well.

[Critterman]

What did that commercial on TV say

I think it was Fram Air Filters


You can pay me now   (buying the air filter)

or you can pay me later  (rebuilding the engine)

[Imaj]

LOL! True Critterman!

[Imaj]

One more question...Is it important to warm up the Diff/Trans fluids before changing them?

[S.P.]

When your changing the fluids, you want to get as much of the old stuff out as possible. Warm/hot oil flows better than cold oil. So I would say yes. 

[SKY888]

MOTUL is a VERY good brand.   All of my friends that professionally drag race/road race/drift in the Philippines use MOTUL.

[Critterman]

and it smells so clean and fresh, like a day at the beach

[Helios]

Going to change out the transmission fluid today to Royal Purple. Hopefully it'll smooth out the shifting.