Need advice on Royal Purple MaxGear 75w90

[Lloyd10977]

I recently purchased a 1995 Ford Explorer Limited 4x4, with Traction-Lok. This vehicle has been extremely well maintained using mostly dino fluids. I plan to change the transmission(ATF), xfer case(ATF), and rear differential(GL-5 SAE 90) using Royal Purple Max ATF and Royal Purple MaxGear 75w90.

The manual indicates that when changing the diff gear lube, 4 ounces of friction modifier should be added. The Royal Purple website indicates that all viscosities of Max-Gear are formulated with hypoid friction modifiers necessary for use in clutch or cone type differentials. No additional additives are necessary.

Suggestions?

 

[Rebel Rouser]

Try it first without any of the "external" friction modifier. If chatter develops, then get a bottle and add some.

Remember to drive several tight figure of 8 patterns in a parking lot after changing the differential fluid out. This helps to work the new lube into the clutch packs of limited slip units.

 

[ULVER]

A lot of the Ford Police Interceptors here in Atlanta use the R/P 85-140 gear oil. I went with it in mine, after hearing good things. I'm sure the 75-90 would be excellent, as well.

 

[MolaKule]

On our Website:

http://www.specialtyformulations.com/index_files/page1458.htm

here is what we recommend:

quote:

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For limited slip differentials, add this fluid and determine if any chatter (stick/slip) exists while doing figure eights in an empty parking lot. This fluid alone will usually be sufficient for LSD’s. If some chatter still exists, try an aftermarket LSD additive in ¼ can/bottle increments.

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[M. Davis]

I have used Max Gear in two separate vehicles that called for friction modifier, and never needed any extra. Max Gear works great. In cold weather it flows much better that the dino fluids.

 

[Lloyd10977]

quote:

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Originally posted by ULVER:
A lot of the Ford Police Interceptors here in Atlanta use the R/P 85-140 gear oil. I went with it in mine, after hearing good things. I'm sure the 75-90 would be excellent, as well.

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So now this brings up an additional question in my mind. Since the spec calls for GL-5 SAE 90, would there be any benefit for me to use 85-140 over the 75-90? The vehicle is equipped with a towing package, and is used mostly on the street/highway with only occasional off road ventures, and on occasionally towing a light-duty trailer.