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nkyhunter

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I have 3.55's e Locker with tow package (not max) and have the 9.75 rear end. I got FRPP Cover. it's 12 pounds of iron vs the thin stamped steel and will absorb a lot more heat. Also if you manage to backup and hit something the iron is way more durable. I changed mine rear cover and oil (used AMSOIL 75-110) out with about 2k miles, there was a very fine black particulate in the pumpkin. Use blue shop towels to wipe out inside the pumpkin. When gears first break in from the factory there is acids and metal that get released from the gear set. I was not going to leave it in... Cover also has magnet drain plug to keep the metal out of the oil/gears. If you are going to do it get the LUBE LOCKER gasket! Really nice and they do not leak.

More durable, absorbs more heat, has magnet, makes change easy, wont rust like cheap stamped steel. No way I was going to wear 'dirty underwear' for the first 80k miles of life.

My picture I took!
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In the end I got this one and now deciding on what gear oil to use, weight 75-90
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SALEEN961

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Ford recommends 75W85 gear oil for our trucks, but they used to recommend 75W140 for the 9.75" and I still prefer using that viscosity for severe use. I normally use Redline 75W140NS and add Ford XL-3 friction modifier, but Redline's standard GL-5 gear oil that already contains friction modifiers is a good option for most people.
 

tony72cutlass's'

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Ford recommends 75W85 gear oil for our trucks, but they used to recommend 75W140 for the 9.75" and I still prefer using that viscosity for severe use. I normally use Redline 75W140NS and add Ford XL-3 friction modifier, but Redline's standard GL-5 gear oil that already contains friction modifiers is a good option for most people.
But only if you have a limited slip like yours right? Not for e-locker but I could be wrong
 

SALEEN961

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But only if you have a limited slip like yours right? Not for e-locker but I could be wrong
Most synthetic gear oils already have friction modifiers added them, and they should all be safe for use with an e-locker or open differential. It can be difficult to find a synthetic gear oil without added friction modifiers in many brick and mortar stores.

Many synthetic gear oils will advertise that no additional friction modifiers need to be added for use with limited slip differentials; but I have had bad experiences in the past, and I prefer to buy gear oil without added friction modifiers so that I can add it myself. Adding it myself gives me control over how much is added, and I don't have to worry about the additive not working well with my clutch packs.

I'll also like to add a bottle of Ford's XL-3 friction modifier to differentials that don't require it after installing a new set of gears because it helps to reduce gear temperatures. In my mind it's just cheap insurance, and I know that some customers aren't going to take it easy while the gears break-in during the first 500 miles like they're supposed to.
 

tony72cutlass's'

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Most synthetic gear oils already have friction modifiers added them, and they should all be safe for use with an e-locker or open differential. It can be difficult to find a synthetic gear oil without added friction modifiers in many brick and mortar stores.

Many synthetic gear oils will advertise that no additional friction modifiers need to be added for use with limited slip differentials; but I have had bad experiences in the past, and I prefer to buy gear oil without added friction modifiers so that I can add it myself. Adding it myself gives me control over how much is added, and I don't have to worry about the additive not working well with my clutch packs.

I'll also like to add a bottle of Ford's XL-3 friction modifier to differentials that don't require it after installing a new set of gears because it helps to reduce gear temperatures. In my mind it's just cheap insurance, and I know that some customers aren't going to take it easy while the gears break-in during the first 500 miles like they're supposed to.
very interesting, I didn’t know they added it into most synthetic oils.

i watched a guy take apart an e-locker on YouTube it’s a pretty simple/cool design.
 

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ok so here are my thoughts on this:

Ford recommends SAE 75W-140 PREMIUM SYNTHETIC HYPOID GEAR LUBRICANT, with XL-3 Friction modifier.

https://www.motorcraft.com/us/en_us...e-75w-140-synthetic-rear-axle-lubricants.html

It has enhanced wear protection for hypoid gears, excellent shear stability and protects from rust and corrosion. This product meets all fill-for-life requirements of Ford Motor Company.

Note: For a complete drain and refill, some limited-slip axles require addition of Friction Modifier, Part Number XL-3 meeting Ford specification EST-M2C118-A. Refer to Workshop Manual or Owner’s Guide.


(in the link for Motorcraft 75W-85 it states:) Do not use in axles here SAE 75W-140 is recommended.

Motorcraft XY-75W140-KL (75w-140 hypoid gear oil) is about $30 a quart and you need 3 (about 2.5) to change it out. Amsoil was less and has the FM in it.

I went with Amsoil 75w-110 severe gear as I wanted a touch thinner for mileage and power, and also I now have a 12lb iron rear diff cover -- it would absorb a lot more heat than the thin stamped steel cover ever could.

Also Amsoil works for Hypoid gears: https://blog.amsoil.com/what-is-hypoid-gear-oil-and-other-gear-oil-questions-answered/

I do not currently 'torture tow' heavy loads through the mountains, campers etc, if I did I'd go Motorcraft XY-75W140-KL with XL-3 - with the Ford Racing cover, (and lube locker gasket!)
 

fordtruckman2003

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ok so here are my thoughts on this:

Ford recommends SAE 75W-140 PREMIUM SYNTHETIC HYPOID GEAR LUBRICANT, with XL-3 Friction modifier.

https://www.motorcraft.com/us/en_us...e-75w-140-synthetic-rear-axle-lubricants.html

It has enhanced wear protection for hypoid gears, excellent shear stability and protects from rust and corrosion. This product meets all fill-for-life requirements of Ford Motor Company.

Note: For a complete drain and refill, some limited-slip axles require addition of Friction Modifier, Part Number XL-3 meeting Ford specification EST-M2C118-A. Refer to Workshop Manual or Owner’s Guide.


(in the link for Motorcraft 75W-85 it states:) Do not use in axles here SAE 75W-140 is recommended.

Motorcraft XY-75W140-KL (75w-140 hypoid gear oil) is about $30 a quart and you need 3 (about 2.5) to change it out. Amsoil was less and has the FM in it.

I went with Amsoil 75w-110 severe gear as I wanted a touch thinner for mileage and power, and also I now have a 12lb iron rear diff cover -- it would absorb a lot more heat than the thin stamped steel cover ever could.

Also Amsoil works for Hypoid gears: https://blog.amsoil.com/what-is-hypoid-gear-oil-and-other-gear-oil-questions-answered/

I do not currently 'torture tow' heavy loads through the mountains, campers etc, if I did I'd go Motorcraft XY-75W140-KL with XL-3 - with the Ford Racing cover, (and lube locker gasket!)
Manual says to use the 75-85 though.
I still have 75-140 from my Gen 12 truck.
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