Rear Differential oil change

[slxne]

Anyone here familiar with rear differential oil changes?

I plan on changing my 2017 PP1 rear differential oil and going with 75-140 since my rear diff is noisy on slow turns and want to quiet it down.
What is the difference between 75-90 and 75-140?

I've been reading forums everywhere and people recommend I go with 75w-90 If I don't track or push the car, Will it harm the rear differential if I go with 75-140?

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[GregO]

I plan on changing my 2017 PP1 rear differential oil and going with 75-140 since my rear diff is noisy on slow turns and want to quiet it down.
What is the difference between 75-90 and 75-140?

I’ve been using Motul Gear Competition 75-140 for several years in my daily driven GTPP 3.73 Torsen. I wouldn’t use anything else but that.

 

[Jstang23]

As long as you stick with 75W I can't imagine it would hurt your diff. But if your diff is noisy then you may need to replace some things inside. What diff do you have?

 

[Optimum Performance]

Anyone here familiar with rear differential oil changes?

I plan on changing my 2017 PP1 rear differential oil and going with 75-140 since my rear diff is noisy on slow turns and want to quiet it down.
What is the difference between 75-90 and 75-140?

I've been reading forums everywhere and people recommend I go with 75w-90 If I don't track or push the car, Will it harm the rear differential if I go with 75-140?

It is likely the additive is broken down and the Torsen is just 'working' better. Ford uses the additive to calm down the Torsen. The 140 will just offer better resistance to heat, maintaining viscosity while hot. It flows the same cold.

 

[cerbomark]

Most auto parts stores carry this. Use the OEM spec weight and this according to the direction in your manual.

 

[Sig556]

If your Diff. is making noise there is a problem. Thicker lube is only a Band-Aid. You may have scored races or a bearing going bad, or even a chipped tooth. Pulling the cover and checking things out is the way to go.

 

[Optimum Performance]

If your Diff. is making noise there is a problem. Thicker lube is only a Band-Aid. You may have scored races or a bearing going bad, or even a chipped tooth. Pulling the cover and checking things out is the way to go.

It makes noise at low speed turns. My car brand new did this from the factory likely because there was no additive in it or not enough. Changed the fluid to BG Ultra Guard LS and it went away, 8 years ago. Its the additive package in his current oil with ??? miles on it that is broken down, not the differential.

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