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DIFF FLUID??

kmanxj5050

NAXJA Forum User
Ok i have searched this a little bit and found vague information.

I am just wanting a common concencus (spelling? lol)/ preference of brand, period between change, and weight (i dont know what to use, 01 D30/C8.25)

And anything else you do to your diff when you change the fluid (brake clean, etc.)

thanks folks:cheers:
 
I use either brake cleaner or electrical cleaner and rags that I throw away afterwards. As for lube, just normal 90w works fine, if you have a limited slip you will ant to add friction modifer, stinky stuff for sure..
 
I have been running the Lucas diff fluid in both diffs and I am running lunchboxs in both ends w/o any problems.
 
I think it is like 85/140

I think they only offer one weight from Lucas, but I could be wrong on that. It is a bit on the heavy side for extreme cold weather, but has worked flawless for me for years. I change diff fluid about every 5000 miles or when ever I have wheeled where there is excess mud and water.
 
If you don't have an owners manual for your Cherokee you should find or buy one. The manual has recommended service intervals, fluid requirements and fluid capacities. There are two service interval charts, one for daily drivers and one for trail or work trucks.

If you commonly drive through deep water on your trail runs you should replace the diff fluids much more often to prevent water contamination and rust inside the differentials.

Any brand name product that the meets the specifications in the manual will be fine. I use synthetic diff fluid and it performs great when temperatures fall below zero.
 
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I've got FSM fluid specs for rigs on my site as well. Since I don't have all FSMs, I don't have all years (yet. Gimme time...) but it should get you started.

Link in sig, go to Tech section. I've just gotten a swale of stuff from Dana, so I'll be doing "unit" pages on various axles soon.
 
For fluid type, I use mobil 1 synthethic 75w-90.

Here's a detailed description of the changing process, is this what you were looking for?

When changing diff oil, you can either pump out the old or take the cover off - if you haven't done it lately it's better to take the cover off so you can look at things. Remember you'll need RTV to reseal the cover. Clean your drain pan good beforehand and then after you've drained the old fluid, inspect it for metal shards and contaminants (light color with bubbles means you got water in it). Look at the exposed gears, and turn the wheels while watching the gears. The edges should be sharp and all the motion very smooth. Clean the diff cover real good - you can use soap or various kinds of cleaners here, but be sure to get rid of all remnants of soap residue or any other contaminant. Inside the diff, use a clean rag and wipe off the grime on the parts you can reach. Then, waste a quart or two of cheap motor oil spraying it over the gears and everything you can reach and then wiping it off. You don't have to get out every remnant of the motor oil, but try to get as much as you can. Clean the mating surface to the cover very good, getting rid of every shred of the old RTV or anything else baked on there. When you've reached shiny metal, apply the RTV and reattach the cover. Fill it with gear oil and drive on happily. Check it regularly for leaks for the first few weeks.
 
It helps to keep things clean by leaving a few bolts in the cover. That way the cover doesnt come falling off spilling fluid everywhere. Leave 2 in the top and 1 at the bottom or something so the cover can open but not come off.

Dont forget to let the RTV cure as per the instructions on the tube...
 
Agree on leaving a loosened bolt in at the top to minimize spills. When you put the cover back on, put a medium bead of silicon on the cover. Put in on and barely snug the bolts by hand. Go have lunch or even wait overnight and give the silicon some time to setup. Then come back and torque the bolts to spec and refill.

If you just toque it down right away you squeeze out all the silicon, which also happens to shrink slightly as it cures. Giving it time to cure a bit means the bead will be under some pressure from the cover when it gets torqued down. This technique works great for valve covers too.
 
From the 92 FSM, diff fluid maint interval is 30k miles for normal conditions, 12k for severe conditions.

Also keep in mind that water severely impacts lube efficiency, so it's also good to change the diff fluid anytime you think you might have gotten water in it.

Question for the group - how does water get in the diff? I would think you'd have to be in water (or have it splash in quantity) over the vent tube openings, which are nearly dash-level on the front of the fire wall (right?). Yet, I got water in my rear diff once when fording water that was only about 3/4 the way up my tires. What happened?
 
92xjsp said:
From the 92 FSM, diff fluid maint interval is 30k miles for normal conditions, 12k for severe conditions.

Also keep in mind that water severely impacts lube efficiency, so it's also good to change the diff fluid anytime you think you might have gotten water in it.

Question for the group - how does water get in the diff? I would think you'd have to be in water (or have it splash in quantity) over the vent tube openings, which are nearly dash-level on the front of the fire wall (right?). Yet, I got water in my rear diff once when fording water that was only about 3/4 the way up my tires. What happened?

Basically it is from the temperature differential between hot/warm bearings and seals and cold water, the cold water gets more or less sucked in. As long as you keep the water below the center point of your axles it will be ok, it will usually be ok too if you roll thru, but if you stop and sit with water above the center line you will get water in there.
 
RichP said:
Basically it is from the temperature differential between hot/warm bearings and seals and cold water, the cold water gets more or less sucked in. As long as you keep the water below the center point of your axles it will be ok, it will usually be ok too if you roll thru, but if you stop and sit with water above the center line you will get water in there.

OK, thanks, that makes sense. I crossed that particular creek about 4-5 times that weekend and it was about 50 feet wide, so there was plenty of time to suck water in. So then, we should add to the diff fluid changing interval, following any time when your axle is underwater for more than a few minutes.
 
thanks for the description ive done it before and the silicon idea of letting it sit is new to me but sounds perfect.


and i only really got one response for diff fluid preference (mobil 1 oh and heavy lucas)

lucas makes a 75-90 that i was thinkin of using
 
My preference for the front and rear differentials, manual transmission and transfercase is Redline Synthetic lubricants.... 75W/90, MT90 and D4 ATF.
Jeep has used Redline since shortly after it was purchase new in '97.
 
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