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5000 miles Front/Rear diff fluid + T-case fluid check results

Since the 392 is always 4 auto or 4h or 4l would it hurt anything to only use 75w/140 in the rear axle and leave the front axle fluid stock?
Opinions are going to vary there. I suggest you read the East Coast Gear paper I posted directly above yours and go from there.

My opinion is yes, you'll be perfectly fine and in the event of a failure, you may end up with a warranty claim where they test the fluid for the weight rating and hold it against you to void the claim, but I sort of doubt it.

I'm not even sure dealers have a machine or some kind of equipment to measure that in the first place. I can tell you this, when they pull the plug, the 75w/140 runs out at the same speed as anything else for the most part (I've changed it out several times), so visually, it's not coming out like peanut butter. I doubt they'd notice the difference.
 
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Since the 392 is always 4 auto or 4h or 4l would it hurt anything to only use 75w/140 in the rear axle and leave the front axle fluid stock?
I can reply as simply as possible. 75w/140 is the best weight fluid you could use for either axle. That weight oil is not recommended by the manufacture of your vehicle, but is recommended by the manufacturer of the axles.
 
Since the 392 is always 4 auto or 4h or 4l would it hurt anything to only use 75w/140 in the rear axle and leave the front axle fluid stock?
You can use 75W140 Front and Rear Diff's as recommended by your axel manufacture Dana.
 
What are most of you running for oil in your 392? I just sold my 2005 LJ with the 4.0 liter and a Banks Turbo and always ran Synthetic.
 
What are most of you running for oil in your 392? I just sold my 2005 LJ with the 4.0 liter and a Banks Turbo and always ran Synthetic.
Our owners manual calls out full synthetic 0W-40 oil meeting MS-0921.
So far the only oil that I'm aware that meets this spec. is Pennzoil Ultra Platinum 0W-40 full synthetic.
LF
 
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