Rear differential (RDU) fluid? Amsoil alternative?

[BouncinBrandon]

Greetings, I'm here to inquire about the rear differential (RDU) fluid for a 2024 Ford Bronco Sport Big Bend 1.5L 3-cyl. I'm an Amsoil guy, and I have compiled a list of Amsoil alternative fluids I'll be switching this new Bronco to, the only issue I seem to be having is with the rear differential fluid. The rear diff seems to call for Motorcraft XY-75W-QL (AKA Motorcraft 75W RDU Fluid), but Amsoil doesn't have a recommended alternative on their site. I called tech support, and they stated they don't recommend any of their products as none of them perfectly match the specifications. What intrigues me are a few people I've seen on the broncosportforum website state how they're using Amsoil's 75W-90 Severe Gear lube in the rear diff. Who would recommend using the 75W-90 Severe Gear lube vs the recommended Motorcraft XY-75W-QL? What specs are missing from the severe gear lube vs the OEM recommendation? Amsoil seems to have an alternative listed for everything else other than the RDU, so worst case if I have to go with the OEM RDU fluid I guess I will, but would love to use a better alternative fluid if possible. Doesn't even have to be Amsoil, perhaps Redline has something I haven't looked into, any input would be much apprecaited!

 

[skyactiv]

Amsoil makes great lubricants and it may work in your application. But don't assume Amsoil and Redline is a better alternative and just because it's working for a few on the web doesn't mean it's okay or best long term.

There are some really specific fluids used in some AWD and 4WD vehicles today. Ford as an example has a 75W Disconnect Rear Drive Unit Fluid. Would you want to try putting Amsoil 75W90 in that because Joe Dumb on the internet said he did and has no problems so far.

I've spoke of it before, I put Motorcraft XT-M5-QS in a 2013 GTI 6 speed manual I once owned. That fluid said made in Germany on the bottle and the MSDS revealed it being a PAO synthetic. I don't think Ford is cheeping out on their non engine oil fluids.

 

[Pablo]

Thread 'Ford Disconnect Rear Drive Unit Fluid (XY-75W-QL)'

Feb 2, 2022

It looks like Ford has a new(ish) fluid to discuss.

XY-75W-QL - Disconnect Rear Drive Unit Fluid​

• Motorcraft® SAE 75W Disconnect Rear Drive Unit Fluid is specifically formulated for Ford disconnect rear drive units with a low offset hypoid gear
• Developed with a lower viscosity to improve axle efficiency and fuel economy
• Motorcraft® SAE 75W Disconnect Rear Drive Unit Fluid is formulated with synthetic base stocks, friction modifiers, antiwear and extreme pressure additives to provide gear protection and smooth clutch operation
• Use only in Ford Disconnect Rear Drive...

• ctechbob
• Replies: 2
• Forum: ATF, Differential, Trans, Brakes, P/S

I would think Amsoil SVL 75W-85 would be a better match. But first change go with the Ford fluid.

I recommend you send a sample of the virgin Motorcraft XY-75W-QL and a sample of the drained fluid for analysis.

 

[#18FAN]

MIL owns a 22 Edge and is due for rear RDU change yes no recommendation from Amsoil. Being that it is under warranty if not running the OEM recommendation I don’t believe you would have a leg to stand on if an issue would arise. I had this problem years ago with VTM Honda recommendation it was OE fluid only basically your on your on if a issue would potentially happen.

 

[97prizm]

Greetings, I'm here to inquire about the rear differential (RDU) fluid for a 2024 Ford Bronco Sport Big Bend 1.5L 3-cyl. I'm an Amsoil guy, and I have compiled a list of Amsoil alternative fluids I'll be switching this new Bronco to, the only issue I seem to be having is with the rear differential fluid. The rear diff seems to call for Motorcraft XY-75W-QL (AKA Motorcraft 75W RDU Fluid), but Amsoil doesn't have a recommended alternative on their site. I called tech support, and they stated they don't recommend any of their products as none of them perfectly match the specifications. What intrigues me are a few people I've seen on the broncosportforum website state how they're using Amsoil's 75W-90 Severe Gear lube in the rear diff. Who would recommend using the 75W-90 Severe Gear lube vs the recommended Motorcraft XY-75W-QL? What specs are missing from the severe gear lube vs the OEM recommendation? Amsoil seems to have an alternative listed for everything else other than the RDU, so worst case if I have to go with the OEM RDU fluid I guess I will, but would love to use a better alternative fluid if possible. Doesn't even have to be Amsoil, perhaps Redline has something I haven't looked into, any input would be much apprecaited!

How long have they been using Redline or amsoil? Does anyone have any really high mileage differentials using the non-oem spec fluid?

 

[Boomer]

I think the originator falls into my "I paid $40,000 for a new vehicle but i want to save a couple of bucks on a fluid that will be changed every few years" category. Why not just buy the approved fluid at the dealer and use it. Emotional attachment to Amsoil does not make it necessarily suitable for your use.

 

[NibbanaBanana]

I emailed ExxonMobil and asked them if I could use their 75w-90 GL5 gear lube in my Aveo transaxle calling for 75w-85 GL4. They said "No." No reason given.

I wouldn't take any chances.

 

[edyvw]

I emailed ExxonMobil and asked them if I could use their 75w-90 GL5 gear lube in my Aveo transaxle calling for 75w-85 GL4. They said "No." No reason given.

I wouldn't take any chances.

No, and I mean NO COMPANY will ever write an email recommending something that is not recommended by manufacturer.
If you catch their engineers over beer, yes. But written statement going against manufacturer recommendations, absolutely, unequivocally NO!

 

[Cujet]

What unique properties does your differential have? The standard version seems to be a clutch based limited slip. The Badlands/FE trim has a electronically controlled dual clutch system that provides more driving torque to both wheels. Uses a light weight gear oil for efficiency. In this case, if there is not a fluid that meets specs, I'd stay with the OEM fluid. The higher the viscosity, the less grip the clutch packs will have. And the additive package can be critical.

The thing is, you might never know the clutch pack has been rendered inop, until you get stuck somewhere and the wheels won't transmit torque as they should.

 

[BouncinBrandon]

I think the originator falls into my "I paid $40,000 for a new vehicle but i want to save a couple of bucks on a fluid that will be changed every few years" category. Why not just buy the approved fluid at the dealer and use it. Emotional attachment to Amsoil does not make it necessarily suitable for your use.

I'd rather use a higher quality fluid if applicable. That being said, there's an Amsoil alternative for every fluid on this vehicle with the exception of the RDU. The reason why I won't use the "approved fluid" is because the so called "approved fluid" is of much lesser quality. You can look up videos comparing Mercon ULV to Amsoil ULV to see how much better Amsoil's transmission fluid is for this vehicle.

 

[edyvw]

I'd rather use a higher quality fluid if applicable. That being said, there's an Amsoil alternative for every fluid on this vehicle with the exception of the RDU. The reason why I won't use the "approved fluid" is because the so called "approved fluid" is of much lesser quality. You can look up videos comparing Mercon ULV to Amsoil ULV to see how much better Amsoil's transmission fluid is for this vehicle.

How do you know it is of lesser quality?
What methodology is used to determine which fluid is better? That is same story on BMW forums. They are tripping over themselves to get something “better” than BMW DTF-1 transfer case fluid. Yet, Ravenol who sells uber, super, mega “full synthetic “ replacement fluid claims DTF-1 is more shear stable. And yet, most people go for Ravenol etc. However, in reality BMW sells ester based Shell made product and no one ever had issues with it.
Is there issue with these units? Is there known failure that can be remedied with better fluid?

 

[Silverado12]

I'm pretty sure the Bronco Sport Big Bend and Outer Banks models w/1.5L motor call for 75W-85 gear lube, or at least they did in 2022. I would use 75W-90 and not think twice about it.

 

[meep]

Fluid compatibility can be pretty simple if it’s just a gear unit. If the unit also has a clutch mechanism, it’s a totally different animal. Like with what @#18FAN may have experienced, the VTM system uses electrically-engaged clutches - and different fluids would potentially harm the clutches or make the system too grabby or not grabby enough. Same with Honda’s dual-pump system the CRV’s used.

If the bronco sport is simply a gear drive in the tail, it won’t be as picky. But yeah, if it has a clutch system in there, limited slip or electronically modulated, stick with the oem stuff for now.

 

[BouncinBrandon]

How do you know it is of lesser quality?
What methodology is used to determine which fluid is better? That is same story on BMW forums. They are tripping over themselves to get something “better” than BMW DTF-1 transfer case fluid. Yet, Ravenol who sells uber, super, mega “full synthetic “ replacement fluid claims DTF-1 is more shear stable. And yet, most people go for Ravenol etc. However, in reality BMW sells ester based Shell made product and no one ever had issues with it.
Is there issue with these units? Is there known failure that can be remedied with be

 

[#18FAN]

Explain what this has to do with RDU fluid.

 

[BouncinBrandon]

Explain what this has to do with RDU fluid.

It doesn't? Did you not read the reply thread? I also wasn't replying to you here lol

 

[edyvw]

I say use Extra Virgin Oil from Costco.
In the meantime check meaning of the word “methodology.”

 

[BouncinBrandon]

I say use Extra Virgin Oil from Costco.
In the meantime check meaning of the word “methodology.”

I can't help you if you didn't want to watch the video. There's clearly a difference between both fluids, and one is clearly inferior. The ignorance in some of these replies is baffling. But hey, I choose to be informed and open minded unlike some. Let me know how that extra virgin works in your transmission, I'll stick with Amsoil.

 

[edyvw]

I can't help you if you didn't want to watch the video. There's clearly a difference between both fluids, and one is clearly inferior. The ignorance in some of these replies is baffling. But hey, I choose to be informed and open minded unlike some. Let me know how that extra virgin works in your transmission, I'll stick with Amsoil.

1. It is not fluid you are looking for. Fluids for different components are, well, different, and often made by different suppliers.
2. You don't have clear alternative. So, I really don't understand the point of that video by some guy in a garage.
2. UOA, or in this case, used fluid analysis, does not mean anything to get a clear answer. It is $50 analysis that is far from conclusive. Hence, an established methodology if you are looking for a conclusive answer.

However, you did not come here to seek answers, but to get confirmation bias.
So, you have two options:

1. Use what you already think you should use, which is Amsoil SVG 75W90.
2. Use whatever FORD recommends, considering there are no official alternatives.

Since there are "CLEAR" differences, as you say, I really don't understand why you did not already purchase SVG 75W90 and filled it over the weekend.

 

[BouncinBrandon]

1. It is not fluid you are looking for. Fluids for different components are, well, different, and often made by different suppliers.
2. You don't have clear alternative. So, I really don't understand the point of that video by some guy in a garage.
2. UOA, or in this case, used fluid analysis, does not mean anything to get a clear answer. It is $50 analysis that is far from conclusive. Hence, an established methodology if you are looking for a conclusive answer.

However, you did not come here to seek answers, but to get confirmation bias.
So, you have two options:

1. Use what you already think you should use, which is Amsoil SVG 75W90.
2. Use whatever FORD recommends, considering there are no official alternatives.

Since there are "CLEAR" differences, as you say, I really don't understand why you did not already purchase SVG 75W90 and filled it over the weekend.

People like you clearly have a hard time reading. I already stated in my original post that if I have to use the OEM RDU fluid I will, and based on the replies here that's more than likely what I'll end up doing until a (trigger warning) higher quality compatible fluid is presented.