Differential oil? Changing? What to use?

Fortuna Wolf

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I tried searching for this. I understand what the transmission is, but what is the differential?
I have a 2002 automatic. Do I have a differential? How do I change the oil in it? Is there a particular standard for this oil that I need to meet, or would a good AMSOIL or Red Line oil work?
 

Beowulf

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Fortuna Wolf said:
Fine then, what is the transaxle, how do I change it?
A transaxle is something that has the transmission and the differential in the same case.

Rear wheel drive cars have the differential (which is a case with some gears in it that transfer the rotation of the drive shaft to the drive wheels) on the rear axle, but VWs are front wheel drive and so have the differential and transmission in the same housing, attached to the front axle.

So, 'transaxle' is just another word for your transmission practically speaking.

Edit:
Removed everything I just typed about changing the gear oil, since it applied to manual transmissions, not automatics.
 
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Fortuna Wolf

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Ok, so my automatic transmission's differential, automatic transmission, and torque convertor are all in the same case and are all serviced by the same oil and oil reservoir? That's why it takes 9 liters of oil!
So all I have to change is the ATF fluid and I'm done? (And I'll bump up the line pressure too, I've noticed it starting to slip a bit in 1st gear)
 

wny_pat

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You got it. Do a search for the proper ATF, cause I don't have a slush box and don't know what it is. Think you can adjust the auto tranny with the VAG-Com if I remember right. Some of the guys here were talking about something like that, but I don't know if it was the 4sp or Tipomatic.
 

Fortuna Wolf

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I have the 4sp. 86k miles, and the clutches are slipping so its due for a fluid change and I'm going to increase the line pressure on it too, but you need to remove the pan to do that. You use vag-com to monitor its temperature and when it gets up to a certain temp is when you top off the fluid.
 

AndyH

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Fortuna Wolf said:
I tried searching for this. I understand what the transmission is, but what is the differential?
I have a 2002 automatic. Do I have a differential? How do I change the oil in it? Is there a particular standard for this oil that I need to meet, or would a good AMSOIL or Red Line oil work?
Fortuna,

Check for a separate fill and drain plug on the differential portion of the transaxle. Some transmissions are filled completely with automatic transmission fluid and some are divided into two sections.

I don't know enough about the transmission types used in our cars, so this is collected from different sources. Please verify this before you start draining fluid.

Bentley says the 01M and 096 transmissions are 4-speed automatics, while the 09A/09B are 5-speed automatics.

The data I have says that the 2002 auto transmissions are filled with VW part G052990A2. The final drives (if separate) are filled with 1.7 pints of 75W-90 GL-4 gear lube.

01M initial fill is 3.2 quarts, total fill (torque converter and plumbing) makes it 5.6 quarts.

http://www.bentleypublishers.com/product.htm?code=vya4
http://www.amsoil.com/scripts/runisa.dll?amsoiloaf:index

I don't have an owners or service manual for the 2002, so that's all the info I can provide.

Andy
 

car54

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The autos have a seperate differential oil. The service literature goes into detail on how to check and add oil to the differential, but not about draining it. This might be a good use for a suction pump. I dont believe there is a differential drain, but Ive never looked.
 

compu_85

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Guys, the diff and the trans use a different oil on the automatic. MoGolf says the only way to change the gear oil in the diff is to use a suction device, like a Pella.

-Jason
 

LurkerMike

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Good old blood red Amsoil ATF all the way in the transmission for me.

Kerma line pressure mod at 32 "clicks".

Car is bone stock (for now) but will spin 1st gear if you floor it from a stop on anything less than perfect traction pavement. The shifts are firmer but I have not heard it bark second or anything neck snapping like that.

I drive at WOT (wide open throttle) allot... on a WOT acceleration, if you lift suddenly the car noses over hard like it is downshifting and hunting for gears much lower than your speed would otherwise call for. These shifts on decell feel really harmful so I am avoiding this condition in all but emergency situations by lifting slowly from WOT if I am below 80 mph or so.

In other words don't floor it at 10 mph and spool up the turbo to say 50 mph and then lift your foot off of the throttle suddenly. These particular parameters are not accounted for very well IMHO so I avoid them.

I only got just less than 2 quarts to drain from my trans pan when I did the filter and Kerma mod. After the first refill, I cycled the trans through the gears with the engine running several minutes and drained and filled a second time to get more old VW ATF out and more new Amsoil ATF in. Another drain and fill was repeated a couple of days later as well. I plan to drain and refill every 10k oil change and do a drain, filter and refill every 20k miles.

I always cut trans filters open and look for paper and metal bits... that will tell you much about the condition that your transmission is in!

My 2000 automatic may fail short of my 250k mile goal, but it will go down shifting firmly and will be nice and clean inside when it does give up... :p
 
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MOGolf

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The original poster asked about the differential, not the transmission.

Drive the vehicle to warm up the fluid.

For the differential fluid you need to remove the speedometer sensor and drive gear. Remove the air cleaner box so you have more room for access down to the sensor/drive gear. You'll need a 24mm socket, IIRC, or use an adjustable wrench. Disconnect the electrical connector and use the wrench to remove the sensor with its drive gear.

Using a suction device like a Pela, suck out the differential fluid. You will want to have driven the vehicle to make this fluid warm or it will be a slow extraction.

Using a long neck funnel pour in .75L of 75W-90 full synthetic gear lube. I use Valvoline and the only place I've found it is at NAPA stores.

Take a look at the speedometer sensor drive gear. The end of it that sticks into the differential has a narrowed tip. The top of the narrowed section is the full mark. The difference between that and the end of the gear is .1L. Wipe off the gear and screw it into the differential, then take it back out to check the level. If overfull, you can use the Pela to extract the extra.

I recommend applying a thin amount of silicone sealant around the "flange" part of the gear the mates flush with the top of the differential case, at the top of the threaded part. If you don't there is a high probability that the fluid you just put in will leak out. (Don't ask how I know.)

Screw in the sensor, reconnect the electrical connector, reinstall the air cleaner box.
 
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LurkerMike

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MOGolf said:
The original poster asked about the differential, not the transmission.
Yes, originally... but then the original poster posted this post that my post was directed at:

Fortuna Wolf said:
Ok, so my automatic transmission's differential, automatic transmission, and torque convertor are all in the same case and are all serviced by the same oil and oil reservoir? That's why it takes 9 liters of oil!
So all I have to change is the ATF fluid and I'm done? (And I'll bump up the line pressure too, I've noticed it starting to slip a bit in 1st gear)
Fortuna Wolf, you are getting me in trouble with your post drifting! :p :D :D :D

Otherwise an excellent post MOGolf!
 
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Dimitri16V

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MOGolf said:
The original poster asked about the differential, not the transmission.

Drive the vehicle to warm up the fluid.

For the differential fluid you need to remove the speedometer sensor and drive gear. Remove the air cleaner box so you have more room for access down to the sensor/drive gear. You'll need a 24mm socket, IIRC, or use an adjustable wrench. Disconnect the electrical connector and use the wrench to remove the sensor with its drive gear.

Using a suction device like a Pela, suck out the differential fluid. You will want to have driven the vehicle to make this fluid warm or it will be a slow extraction.

Using a long neck funnel pour in .75L of 75W-90 full synthetic gear lube. I use Valvoline and the only place I've found it is at NAPA stores.

Take a look at the speedometer sensor drive gear. The end of it that sticks into the differential has a narrowed tip. The top of the narrowed section is the full mark. The difference between that and the end of the gear is .1L. Wipe off the gear and screw it into the differential, then take it back out to check the level. If overfull, you can use the Pela to extract the extra.

I recommend applying a thin amount of silicone sealant around the "flange" part of the gear the mates flush with the top of the differential case, at the top of the threaded part. If you don't there is a high probability that the fluid you just put in will leak out. (Don't ask how I know.)

Screw in the sensor, reconnect the electrical connector, reinstall the air cleaner box.
Is the fluid suppossed to be GL-5 for the auto differential or GL-4 ?
Never had an auto car but I heard the older VW auto trannies liked to pump the differential with ATF , thin the gear oil and wear it out prematurely. There was a seal there that wasn't doing it's job properly
 

MOGolf

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Spec is only 75W90 synthetic gear oil. Does not specify GL-5 nor GL-4. I've been running the Valvoline 75W90 Syntec full synthetic for many miles in my differential. I also know of a A4 platform manual tranny running it without a problem though it is labeled as GL-5.
 

Fortuna Wolf

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ah! I thought this thread was dead. Thanks for the excellent post MoGolf.

I'm not entirely sure what I'm doing actually (hehehe).

I've heard that the differential oil hardly ever needs to be changed. Since i sounds like its sort of "easy" would it be bad to include this as part of normal maintenance while changing my ATF fluid? IE, does changing the oil too often cause problems?

MoGolf, also, the sealant, is this a sealant that stays liquid, or that hardens like silicone gasket sealant?
 

MOGolf

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Normal RTV silicone sealant will do. You don't need much.

I'd recommend making it a part of normal maintenance at 80K miles.
 

Fortuna Wolf

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Ok, I know its been a while but I want to update this thread.
I purchased myself a 2.5 gal oil boy on sale for $40. (yay). Actually, it was mismarked on the shelf, it rang up for $53, but they changed it for me.

I should have changed this fluid a long time ago. It was dark brown and full of little bits of stuff. The sensor has a 26mm hex thingy, but you should be able to undo it by hand without resorting to wrenches. I wasn't able to get an open ended wrench down to the 22mm head on the actual gear sensor, so I had to use a socket.
26 and 22mm! Not 24. Then again, on my car I had 12mm triple square bits for the CV flanges (supposed to be 8 or 10mm), so YMMV.

I put in 1L of Red Line 75w90. I need to go fetch another L.
 
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JettaTDIBlack

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Anyone have any issues using Valvoline SynPower 75w90 gear oil? I only ask because it is API GL-5 spec and VW spec is GL-4 and GL-5 from what I have read isn't always backward compatible.
 

truman

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Anyone have any issues using Valvoline SynPower 75w90 gear oil? I only ask because it is API GL-5 spec and VW spec is GL-4 and GL-5 from what I have read isn't always backward compatible.
It is my understanding that Synpower is fine for this application. It is what i used in my 05 passat differential.
GL5 is fine because there are no bronze components in the differential from my understanding. At 250k the old fluid was 1/2 low, reasonably clear, with what looked like rust particles.
 
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