Regal AWD PTU(transfer case) fluid change DIY

[G-658934]

I took the time today to change the factory fill in the PTU unit. For someone who has a lift this is an easy 15 minute job using minimal tools. I did it on my garage floor using ramps and jacks and it took about an hour. Mileage was 15,400, 90% highway.

The PTU uses a ACDelco specific fluid p/n 19351882. It has a list price of over $90USD/quart! The description shows it's a 75w-90 synthetic gear lube with EP additives. I was tempted to use some 75w-90 gear lube I have in the stash but with a new transfer case price of $1k or more plus install I bought the fluid from the dealer. I knew it was pricey so I told my dealer to help me out on the price so I walked out for $55+tax. Several online sellers are close in price but charge a ton for shipping so I was happy with the price.

I drove the car up on my Rhino ramps and then jacked up the rear. Making sure the car was level front to back and left to right I then added jack stands under the rear for extra safety.
View attachment 20654

The fill plug and drain plug are closest to the right side of the PTU and I found going under the front of the car to be the easiest to get a good view.
Fill:
View attachment 20655
Drain: (sorry about the angle)
View attachment 20656

You can see that both are identical and have a 3/8" square drive head and there was plenty of room to fit my 3/8" drive ratchet into both.

First step on any differential change is to make sure you can refill it! Remove the filler plug first, then the drain plug. I estimate the torque was between 15-20lb-ft. I put a clean drain pan underneath so I could get a visual on the fluid. It was a bit darker than new but not horrible.
View attachment 20657
The drain and fill plugs were identical and both were magnetic. The drain plug on the right has most of the metallic crud on it.
View attachment 20658
View attachment 20659
If you have the car on a lift over your head filling is pretty easy but there is limited access. I needs to be pumped up to the PTU. I chose to fill it from the top using 3 feet of 1/4" clear tubing that I ran behind the engine. I bought a new 2oz/60cc syringe from a hardware store from the equine section. If I did it again I would use 3/8" tubing as it was the bottleneck and try to find a bigger syringe. The specified capacity is 0.69qts according to GM. That translates to 22oz. I put 23ish oz. in mine before the fluid was dripping out.

I didn't want to waste any of this precious proprietary fluid and only lost about an ounce in the process.

Let me know if you have any questions.

Does the rear differential take the same AC Delco fluid

 

[Jmlo96]

Does the rear differential take the same AC Delco fluid

No it takes Dexron LS.

 

[Hunter Mike]

No it takes Dexron LS.

P/N 88862624 in the US

 

[JulioMaximino]

I took the time today to change the factory fill in the PTU unit. For someone who has a lift this is an easy 15 minute job using minimal tools. I did it on my garage floor using ramps and jacks and it took about an hour. Mileage was 15,400, 90% highway.

The PTU uses a ACDelco specific fluid p/n 19351882. It has a list price of over $90USD/quart! The description shows it's a 75w-90 synthetic gear lube with EP additives. I was tempted to use some 75w-90 gear lube I have in the stash but with a new transfer case price of $1k or more plus install I bought the fluid from the dealer. I knew it was pricey so I told my dealer to help me out on the price so I walked out for $55+tax. Several online sellers are close in price but charge a ton for shipping so I was happy with the price.

I drove the car up on my Rhino ramps and then jacked up the rear. Making sure the car was level front to back and left to right I then added jack stands under the rear for extra safety.
View attachment 20654

The fill plug and drain plug are closest to the right side of the PTU and I found going under the front of the car to be the easiest to get a good view.
Fill:
View attachment 20655
Drain: (sorry about the angle)
View attachment 20656

You can see that both are identical and have a 3/8" square drive head and there was plenty of room to fit my 3/8" drive ratchet into both.

First step on any differential change is to make sure you can refill it! Remove the filler plug first, then the drain plug. I estimate the torque was between 15-20lb-ft. I put a clean drain pan underneath so I could get a visual on the fluid. It was a bit darker than new but not horrible.
View attachment 20657
The drain and fill plugs were identical and both were magnetic. The drain plug on the right has most of the metallic crud on it.
View attachment 20658
View attachment 20659
If you have the car on a lift over your head filling is pretty easy but there is limited access. I needs to be pumped up to the PTU. I chose to fill it from the top using 3 feet of 1/4" clear tubing that I ran behind the engine. I bought a new 2oz/60cc syringe from a hardware store from the equine section. If I did it again I would use 3/8" tubing as it was the bottleneck and try to find a bigger syringe. The specified capacity is 0.69qts according to GM. That translates to 22oz. I put 23ish oz. in mine before the fluid was dripping out.

I didn't want to waste any of this precious proprietary fluid and only lost about an ounce in the process.

Let me know if you have any questions.

Did you replace the PTU Fluid and Rear Diff Fluid? If so have part numbers?

 

[mike69440]

Did you replace the PTU Fluid and Rear Diff Fluid? If so have part numbers?

Thank you this maintenance is on my List.

 

[Slim69]

Thanks for the write-up. I did the PTU and rear diff. today at 16,200 miles (2019 TourX). The PTU is MUCH easier to do than my MAZDA CX-9. I had to suction the fluid out of the Mazda as there was no drain plug.

 

[a200qa]

Does anyone know of an obdII app that will bleed the rear diff clutches? The service manual requires that the clutch system be bled after an fluid change (see attached pics). I have tried "car scanner" with a dongle as well as my OBDII reader - neither hasa rear diff scan function.

Thoughts?

Thanks

 

[SpacemanSpiff]

You need a reader that supports the GM protocol, GDS2 to access features like that.

I've seen this recommended in the past: VXDIAG VCX NANO Fit for GM/for OPEL GDS2 Diagnostic Tool IMMO Programming WIFI | eBay

 

[a200qa]

You need a reader that supports the GM protocol, GDS2 to access features like that.

I've seen this recommended in the past: VXDIAG VCX NANO Fit for GM/for OPEL GDS2 Diagnostic Tool IMMO Programming WIFI | eBay

Hmmm - very helpful. Thank you

 

[Displayhawk]

I am a big believer in aftermarket additives that have been used safely for years, so I used a 60cc equine syringe and some clear tubing that I got from Tractor Supply to pull out 4 oz. of gear oil from the the PTU and the rear differential. I then added 4 oz. of LubeGard #42851 Limited Slip Supplement to each unit. BTW, the whole story of how LubeGard developed their LXE (Liquid Wax Ester) fluids to replace Sperm Whale Oil is on their website and is quite interesting.

 

[OCOMEON]

Does the rear differential take the same AC Delco fluid

Perhaps I'm overlooking it (tired eyes), but I don't see the amounts needed for both PTU and differential fluids. Is it one quart each? Thanks.

 

[acaceca]

The actuator is filled with Pentosin CHF11S fluid. It's a hydraulic fluid that activates the clutches. It is not in the hypoid gears where the most wear is.

I don't plan on changing mine.

The rear diff lube is 75w-90 with a limited slip additive, like Mobil 1 75w-90LS, Castrol Syntrax 75w-90LS, and others. You can buy it from your dealer or the aftermarket, your choice.

 

[Somebody Else]

Just a note for the GS owners looking to follow this, there is a heat shield that blocks the fill port. The heat shield appears to be secured with several torx bits. In general, access is tight given the header running right there. I will get pictures next time I am under the car.

 

[mike69440]

Attached I share a plagiarized set of instructions I made for myself.

 

[Wlepse]

Thanks for sharing the write up.

 

[Displayhawk]

If you look at the VOA I sent to analyze its not a very strong additive package. One of the gear oil guys on BITOG says that a non-LS gear oil would be a good substitute. I’ll wait until after warranty to try Amsoil Severe Gear. An email from Amsoil says that they don’t have a fluid that is suitable so I’m a little apprehensive.
https://amsoilcontent.com/ams/lit/databulletins/g2043.pdf

I too sent an e-mail to Amsoil to see if they had a gear oil for my 2019 Sportback Essence AWD, and they replied they did not. When I search on Royal Purple and Castrol websites, they list one, so kind of surprised at that. I will probably go with Royal Purple and change the Rear Differential and PTU gear oil next spring. Right now the car just turned over 20k miles, and I have LubeGard and Motorkote treatments in each, so it should be good till then. I have attached Product Data sheets for both Royal Purple and Castrol Gear Oils.

 

[Somebody Else]

Just a note for the GS owners looking to follow this, there is a heat shield that blocks the fill port. The heat shield appears to be secured with several torx bits. In general, access is tight given the header running right there. I will get pictures next time I am under the car.

Finally got time to work on the car. For those that are curious, the heat shield (red) is secured with T30 screws but access is tight. I chose to bend the heatshield back to expose the fill port (green) and then bend it back. Blue is the drain port.