PTU & Rear Differential Fluid?

[Displayhawk]

I am going to change the 75W/90 Gear Oil in my PTU and Rear Differential soon, but I am trying to decide on what Gear Oil to use? I sent an e-mail to Amsoil, and apparently their Amsoil Severe Gear oil DOES NOT meet GM specifications. So then I was going to use Royal Purple Max Gear oil, but now I'm hearing good things about Triax Synergy Gear Max oil. Does anyone have any experience with it? It is about half the price of Royal Purple, but say's it's good for 500,000 miles! So essentially a lifetime gear oil. (I personally would never leave it in that long though!) I will admit that I am one of those people that will try something new if it is indeed better than OEM.
I have attached product data sheets for both Royal Purple and Triax gear oils.

 

[ConeDodger]

I paid for a bottle of GM transfer case fluid. Part number 19351882 and it's $100 for about a quart. The dealer might not stock it, apparently it's only for this car. IDK if it's the same for the rear diff or not, just for the transfer case, not sure if that's what you mean for power takeoff unit, probably.

 

[Displayhawk]

I tried the Oil Selector function on the Royal Purple website, and it showed RP 75w90 Max Gear for the Rear Differential only, so I sent them an e-mail asking why it doesn't show the same for the PTU, and got this for a reply.


Thank you for contacting us!
We are very sorry our Royal Purple Oil Selector function did not recommend an oil for your 2019 Buick Regal Sportback Essence AWD power transfer unit (PTU) application. Our third party Oil Selector function on our website, unfortunately is still a little glitchy and we are still working on some systemic problems like omissions, errors and some other bugs and hope to have them ironed out very soon. Thank you for bringing this unfortunate omission to our attention.

Yes, Royal Purple Max Gear 75W-90 (part #01300, quart bottle), is exactly what we recommend for your 2019 Buick Regal Sportback Essence AWD, for your rear differential and also for your PTU.

Max Gear: MAX GEAR® | Royal Purple

Your rear differential takes 0.95 quarts.

Your PTU takes 0.75 quarts.



Thank you for choosing Royal Purple!
Best Regards,
James Morrissey
Sr. Automotive Technical Support
--------------------------------------------------------------------------------------------------
ph 281 354 8600 (x263) fx 281 354 7600
email: jmorrissey@royalpurple.com
email: James.Morrissey@calumetspecialty.com
One Royal Purple Lane Porter, TX 77365

 

[saab93driver]

Is ours is silimlar to the Lacrosse with rear needing 2 fluid types?

 

[Displayhawk]

Is ours is silimlar to the Lacrosse with rear needing 2 fluid types?

There is two parts to the differential. One part has clutch packs and takes the Pentosin CHF hydraulic fluid, while the other part has the gears. It takes the 75w90 gear oil. There is very little wear in the clutch pack area, so the Pentosin CHF is essentially a lifetime oil. I have no plans to replace it. The gear oil is what I am going to replace.

 

[2018 TourX in Texas]

There is two parts to the differential. One part has clutch packs and takes the Pentosin CHF hydraulic fluid, while the other part has the gears. It takes the 75w90 gear oil. There is very little wear in the clutch pack area, so the Pentosin CHF is essentially a lifetime oil. I have no plans to replace it. The gear oil is what I am going to replace.

I'm pretty certain I saw Pentosin CHF at O'Reilly Auto, prob around $20 / Qt.

Seems like Mobil 1 75/90 Syn Gear Oil would be great in the diff gears.

Agreed ?

 

[Displayhawk]

I'm pretty certain I saw Pentosin CHF at O'Reilly Auto, prob around $20 / Qt.

Seems like Mobil 1 75/90 Syn Gear Oil would be great in the diff gears.

Agreed ?

I haven't personally checked out Mobil 1, but you would think it would be good as well. What is weird is that Amsoil Severe Gear or any other gear oil won't work in our cars?!? I have sent an e-mail to them (Amsoil) asking about it, and they said it wasn't what GM specified.

 

[2018 TourX in Texas]

Right on.
Yeah the Mobil1 Syn Gear oil is tops for Diffs & Tcases where 75/90 is specified.
Dunno why Amsoil is not.

 

[Displayhawk]

Since the weather was nice this past weekend, I changed the Gear Oil in both my PTU and Rear Differential. I went with Royal Purple Max Gear 75w90 for both. I really can't tell the difference from the factory Dexron LS fluid while driving, but I have only driven it about 50 miles total since the change. There was about 3/16" of metallic build-up on the magnetic drain plugs when I removed them. The oil in the rear differential seemed to be a darker amber to black color when I drained it vs. the brown amber color in the PTU.
BTW, Dexron LS Gear Oil is made by Petro-Canada Lubricants. I have attached the PDS for it below. 2018 TourX in Texas was asking about the Mobil 1 Syn Gear Oil, so I attached the PDS for it also.

 

[Maxxx]

I recently bought a used TourX and I have a lot of questions )) . I want to change all the fluids in the AWD system. But there is very little information about the points for the all-wheel drive service. I found information on only two points: rear gear (recommended Rear Axle Gear Oil Dexron LS and front gear (recommended Differential Clutch Fluid Pentosin CHF ).
Please tell me how many 4WD service locations are there really?

 

[Jmlo96]

I recently bought a used TourX and I have a lot of questions )) . I want to change all the fluids in the AWD system. But there is very little information about the points for the all-wheel drive service. I found information on only two points: rear gear (recommended Rear Axle Gear Oil Dexron LS and front gear (recommended Differential Clutch Fluid Pentosin CHF ).
Please tell me how many 4WD service locations are there really?

I don't believe the Clutch Fluid really gets changed. It's a hydraulic fluid and a bleed procedure from what I understand.

The two AWD service locations that people service are the transfer case (located up by the Engine) and the rear differential. Both are very easy to service with normal drain and fill plugs. I highly recommend getting the factory fluids as it's a gray area as to what exactly the fluid requirements are.

Transfer case uses the ACDelco 19351882 (AKA unicorn tears) that's about 80-100 dollars for a quart. Only one bottle is needed.
Rear differential uses the Dexron LS that's about 15-20 dollars on Amazon. Only one bottle is needed here too.

 

[Maxxx]

Thanks a lot! Now everything is clearer to me.
I have only one question left. What is this Pentosin CHF 88901975 liquid for, which is mentioned in the manual 🙂)

 

[Jmlo96]

The Pentosin is the clutch fluid.

 

[Phildirt]

Hi everyone. My 18 TourX was making the moaning / vibrating noise out of the diff 2 weeks ago (similar to the noise in the Aisan-equipped Honda CRV's: their fix is THE DIFF FLUID SERVICE mentioned here)! Reading this forum convinced me to buy 2 quarts of Dextron LS (limited slip) diff fluid. It takes a 10mm HEX key or male socket BUT BUT BUT...the refill plug has very limited distance as a bar/bracket nearly blocks access. In stead of a 3/8" ratchet, had to punch the 10mm bit out of a Harbor Freight socket, push the bit into the fill plug and use a 10mm 6point box wrench to twist the bit and break the plug free. This sounds hard but "It's Not" you just made your own tool for your Buick!
Once free, spin the plug out and then pop the lower drain plug! Amazon had the LS fluid for $18.99/qt and a cheap bottle pump filled the diff back up. It did in fact take 0.9 qts. Suspecting I'd find a fuzzy mouse on the end of the magnetic plug, I bought 2 quarts and will redo this after 5k.
Results: the noise instantly reduced about 75% and the vibration improved about 50% "Just backing off the rack and driving down the street". Both conditions continued to improve over 3 days / 1,000 miles to ZERO vibration and on a cold day, you, MIGHT hear the moaning: it's nearly gone!
My car was bought used @ 32K, now showing 71K on the clock... "Hope this helps..." Phil In Cincinnati

 

[Displayhawk]

My (original) rear differential went bad at approximately 50k and had to be replaced. Fortunately, the Buick dealership replaced it under warranty approximately a year ago. The service advisor told me that the original rear differentials were made by a previous vendor with inferior materials. The replacement rear diff was from a different vendor because there were so many replacements under warranty is what the service advisor told me.
But now I am thinking I would like to change out the "Break In" gear oil that's in the rear end diff. Trying to decide between the AC Delco gear oil or the Triax 75w90 gear oil. I have heard good things about the Triax, and their gear oil exceeds all OEM specs.